This landmark 10,500m² building, hidden behind a giant green wall of 350,000 plants, is the first new build scheme to achieve a Nabers UK 5.5-star ‘Design Reviewed’ target rating for landlord energy consumption. Its designers also set out to minimise upfront embodied carbon. The as-built figure of 620kg CO_2e.m^-2 is impressive given that, when it was designed in early 2020, there were ‘no targets and no definition for 90% of what we were talking about’, says Wyatt.

The building has been developed by ECF (formerly The English Cities Fund), a joint venture between developer Muse, Legal & General and Homes England. Its outstanding green credentials are the result of a committed developer and it being the first scheme to be built to Muse’s sustainable development brief, which Cundall helped draft.

‘We worked with Phil Marsden, from Muse, from RIBA Stage 0, to help set the brief for the entire design team at the beginning,’ says Wyatt. ‘We set clear objectives, aspiring to achieve the lowest carbon, the best health and wellbeing, and the best biodiversity increase we possibly could’.

The building’s holistic sustainability strategy means that it is Well Building Standard-enabled. Wyatt says this will ensure its tenants can achieve Well certification with their category B fit-out and its subsequent operation. ‘We went through a fit-out pre-assessment, so the landlord has already obtained 20-30% of the credits needed for any occupier coming to Eden who is looking to Well certify,’ he explains.

Wellbeing features incorporated into the landlord’s design encourage tenants to use the stairs, rather than take the lift, by incorporating daylight into the stair core and locating it so it’s easily accessible from reception.

Fresh air supply rates have also been increased on the office floors. The building’s location on a major road junction precluded the use of openable windows, so it has a full mechanical ventilation system. At the time of its design, most commercial offices had a fresh air rate of 12L.s^-1 per person, but, at Eden, this has been increased to 16L.s^-1 per person, which, Wyatt says, gives much better air quality.

A 4-pipe fan coil system is used to maintain comfort on the office floors, with heating and cooling provided by roof-mounted air source heat pumps. The fan coil units are supplied with fresh air ducted to the rear of the units from roof-mounted air handling units (AHUs).

The increase in fresh air supply rate enables an element of free cooling to be provided by the AHUs. ‘Too much air and you have an energy penalty, but a 16 L·s^-1 per person, the balance is about right; you get an energy increase for the fans, but you get an energy benefit from the free cooling,’ explains Wyatt.

Cooling loads have been kept low by the designers adopting a small power load of only 8W.m^-2. At the time, the British Council for Offices’ (BCO’s) recommended a small power load of 25W.m^-2, based on historic technologies, which, Wyatt says ‘would have caused everything to be oversized and to work inefficiently’.

The ‘punched’ windows allow the building to achieve good daylight levels on the office floors

To come up with the more appropriate small power load, Cundall worked with the project’s MEP concept engineers, Atelier Ten. ‘We convinced Muse to very bravely go for 8W.m^-2, which is enough to power a laptop and monitor,’ says Wyatt. Adopting this lower figure meant that, when the building was first marketed, it was not BCO-compliant. However, the BCO has subsequently updated its guidance to 6W.m^-2.

In addition to allowing for a reduced small power load, the design cooling loads are also kept to a minimum by the building’s envelope. This eschews curtain walling in favour of a solid façade with what Wyatt calls ‘punched’ windows, as opposed to using full-height glazing.‘We said we wanted to achieve an overall façade U-value of circa 0.6 to 0.65W.m^-2.K^-1, which is very challenging to achieve with curtain walling,’ says Wyatt. This has resulted in a façade where the solid areas have a U-value of just 0.15W.m^-2.K^-1, while the windows have a U value of 1.4W.m^-2.K^-1. Airtightness is 2m³.h^-1.m^-2 @ 50Pa.

What gives the building its unique appearance is that the solid elements of the façade are covered by a living wall of 350,000 plants. These form a surround to the windows and, because they are visible from inside the building, Wyatt says they contribute to biophilic health and wellbeing. Other benefits of the green wall include: contributing to the area’s biodiversity; absorbing pollution; reducing the urban heat island effect; and helping to lower the air temperature slightly around the heat pumps, which improves their performance.

In terms of cost, Wyatt says the façade was cheaper than a lot of other systems because, behind the greenery, it is ‘a very basic system’. There will be ongoing maintenance costs, however.

Daylight levels on the office floors are also based on Well criteria, rather than on daylight factor. The office floors are described by Wyatt as ‘reasonably narrow’, but through careful design, the punched window solution achieves good daylight levels.

Climate-based daylight modelling was used to optimise the location of the façade’s 40% glazed area. ‘We did a lot of solar modelling of the façade; we’ve distributed the glazing so there is slightly less on the south and slightly more on the north, to help create uniform daylight distribution,’ explains Wyatt.

Optimising the position and area of glazing, combined with additional shading from the green wall, helps keep solar gains to a minimum. To ensure the offices are comfortable, the fan coil units are controlled zonally, based on four zones per floor. At the time the scheme was designed, Wyatt says a lot of commercial offices were designed to maintain an internal temperature of 22°C, with very little leeway, which meant simultaneous heating and cooling could occur on the same floor plate. For Eden, the heating setpoint is 20°C, while the cooling is set at 25°C.

Wyatt is keen to explain that, even with a 5K dead band, there is no compromise on comfort because the scheme has been designed based on maintaining the operative temperature, which is a combination of air temperature and radiant temperature. He says spaces with full-height glazing often have a high radiant temperature, so a low air temperature is required to maintain a comfortable operative temperature.

The green wall of 350,000 plants incorporates automatic irrigation, fed using rainwater harvested from the building’s roof

At Eden, optimising the glazed area and incorporating a green wall has helped reduce radiant temperatures in the offices, enabling the air temperature to be elevated while still maintaining a comfortable operative temperature. ‘Even though we have a higher air temperature within the space, the operative temperature is the same or better than that of a fully glazed office building,’ Wyatt explains.

The higher air temperature in the offices is just one element of the building’s outstanding low-energy design that has helped it achieve a Nabers UK 5.5-star ‘Design Reviewed’ rating. Nabers is the energy efficiency rating system that is gaining traction because a commercial office’s predicted energy performance is subsequently verified once the building is operational, through annual energy consumption monitoring.

Wyatt says experience from Australia (where Nabers originated) shows that, when a building is first occupied, its Nabers rating is expected to drop by about one star. ‘The idea is that the rating improves over a couple of years as the building is fine-tuned,’ he adds. ’According to the Better Buildings Partnership, we can probably expect a half-star incremental increase each year; so, if we achieve 4.5 stars in the first year, we would expect 5 stars in the second, and 5.5 stars in the third, which would be a really positive story.’

Cundall is already working with some of the building’s future tenants to ensure they don’t compromise the Nabers rating. Alongside the tenants, Wyatt says one of the greatest challenges was ‘ensuring that requirements for operational energy, embodied carbon and biodiversity net gain were written into the building contract in a meaningful way, with a clear methodology for measuring, reporting and certifying performance in use’. This meant providing contractor Bowmer + Kirkland with evidence that the design would work. Bowmer + Kirkland will update the rating using as-built information now that it is complete.

Wyatt says a key lesson from this project is that bringing the Nabers independent design review forward from RIBA Stage 4 (technical design) to Stage 3, when designs usually go out to tender, would give contractors more confidence in the operational energy requirements, although this means doing the calculations and simulation much earlier.

Once fully occupied, Eden will be enabled to run solely on 100% renewable electricity, which will further enhance its already outstanding sustainability and wellbeing credentials. 

About the author
Simon Wyatt MCIBSE is a partner at Cundall and chair of the CIBSE Knowledge Generation Panel

The post Case study: Manchester’s garden of Eden appeared first on CIBSE Journal.

This groundbreaking scheme sets a new benchmark for zero carbon educational buildings – an achievement acknowledged at the 2024 CIBSE Building Performance Awards, where it won Project of the Year – Public Use. The judges said the design team met the brief with an exceptional design that successfully combined ‘high-performing building fabric and high-performing engineering services’.

The school’s exemplary eco-credentials responded to the client’s ambitious ‘One Planet Living’ brief and were supported by planning requirements. Its location, between a conservation wetlands area on Metropolitan Open Land and the pioneering BedZED eco-village, meant that the school had to be zero carbon in operation, effectively, to gain planning approval.

Architype, the scheme’s architect and Passivhaus designer, suggested the Passivhaus Plus standard. ‘In 2014, we said, if you want to get this over the line with the planners you need to say you’re net zero, and the only way we believe you can demonstrate that is through Passivhaus Plus,’ says Christian Dimbleby, an associate at Architype, which worked with engineer Introba to develop the scheme.

The school stands on a shallow, insulated, concrete-raft foundation, incorporating ground granulated blast-furnace slag – a by-product of iron production – as a binder to lower the slab’s embodied carbon.

Its foundation is the only major non-timber element in the two-storey school’s construction. The entire superstructure, walls, roof, composite window frames, first-floor slab and cladding are all formed from timber, after Architype used ECCOlab software (an energy, carbon and cost calculator) early in the design process to select materials with low embodied carbon.

To further reduce emissions, all soil excavated during construction has remained on site and has been used to create grass mounds that surround the playgrounds.

To minimise future embodied carbon emissions, partitions between rooms are designed to be moveable, to allow spaces to be easily reconfigured as the school evolves. Similarly, the school is designed to be extended easily to accommodate an increased pupil intake, without the need for reconfiguring the existing structure or major interventions on the building services.

‘We’ve designed the building so the circulation spaces, assembly hall and plant work for a two-form entry,’ says Dimbleby.

The west, east and south elevations of Hackbridge Primary School

As a Passivhaus building, the L-shaped school has a highly insulated and airtight envelope, to minimise fabric heat losses, control heat gains and provide excellent levels of comfort. The large school hall is positioned facing east-west and serves to help block traffic noise from the nearby main road. The hall shelters the adjoining classroom wing, which faces north-south to optimise solar gains.

Brise soleil and an oversailing roof provide shade to the southern elevation to prevent the classrooms from getting too warm in summer, in compliance with Passivhaus overheating criteria and CIBSE TM52.

‘We did a lot of work with Introba on optimising window positioning and sizing,’ Dimbleby explains.

Classrooms have mixed-mode ventilation, allowing teachers to open windows when conditions are suitable.

In winter, heating is provided by an ICAX 70kW ground source heat pump (GSHP) system. This extracts heat from the ground via eight, 130m-deep boreholes and stores it at 42^oC in a 300-litre thermal store.

A low-temperature hot water circuit, operating at 42^oC flow/37^oC return, supplies low-temperature radiators in the classrooms and an oversized heating coil in the air handling unit (AHU).

‘One of the benefits of Passivhaus levels of fabric insulation is that we didn’t have to locate the radiators under the window,’ says Graham Day, associate principal engineer at Introba.

The school meets LETI embodied carbon targets

Using the ground as an interseasonal heat store enables the boreholes to provide cool water to temper the fresh air supply in summer. In this mode, the heat pump is bypassed so that ground-temperature water (at about 10^oC) is circulated to the AHU cooling coil. Coolth is also recovered from exhaust air by the AHU’s thermal wheel.

‘While we’re extracting coolth from the ground we’re warming it up, which helps the heat pump operate more efficiently in winter,’ Day explains. Because supplying cooling only requires a very small amount of power to run the circulating pumps, it is beneficial to do so, adds Day, because it enables the heat pumps to work more efficiently in winter. ‘It is better than free cooling – it is beneficial cooling,’ he says.

For optimum system performance, annual heating and cooling loads should be balanced, so the heat removed from the ground in winter is put back in summer. ‘On this scheme, we’ve not managed to achieve a precise balance, but there is still a beneficial heat exchange,’ Day says.

Opening windows are key to the Passivhaus strategy

A separate 40kW heat pump connected to the same borehole array is used to preheat the domestic hot-water thermal store to 52^oC. A gas-fired water heater is used to provide top-up heat to the vessel and is available to provide backup to the heating system. ‘Improvements in technology mean that, if we were designing the system today, we’d be able to heat the domestic hot water entirely by heat pump,’ explains Simon Ebbatson, senior principal at Introba.

The temperature in the domestic hot-water network is maintained using a conventional circulation system, but with microbore pipework connections to individual taps.

‘Passivhaus penalises you heavily on dead-leg lengths, so we’ve designed the system to ensure there is no more than a litre of water in any one of these,’ says Day.

To achieve Passivhaus Plus, the school must offset all energy use over the course of a year, including unregulated loads. To do this, it incorporates 424m² of photovoltaic (PV) panels, designed to deliver 81kWp. The panels are supported on frames above the green roof, where a symbiotic relationship means that panels provide shade to the vegetation, while transpiration from the vegetation and evaporation from the growing layer,help cool the panels, improving their output.

Figure 1: EUI of Hackbridge Primary School compared with CIBSE typical and good practice, and LETI school benchmark

The downside of using PVs to achieve an energy balance on a school is that the panels provide the highest electrical output on summer days, when the school is closed. While the school can sell this surplus electricity to the Grid at a relatively low price, it does still have to buy electricity from the Grid at a much higher price to make up for the electricity shortfall on shorter, darker winter days. The school achieves an annual energy balance, but there is still a net cost for electricity. ‘Unfortunately, achieving an energy balance does not necessarily result in a financial balance in today’s market; we hope this may change in future,’ Day says. See Figure 1 for energy performance data.

The school received its first intake of pupils just before the Covid pandemic, which hindered its operational optimisation and, subsequently, its ability to achieve net zero energy in operation. There were also issues with a faulty buffer vessel and three of the photovoltaic inverters failed. School staff, too, struggled to come to terms with the nuances of running a Passivhaus Plus school – for example, knowing when to open the windows and when to take advantage of free cooling.

To their credit, the engineers and architect have remained committed to the project and have continued to be involved through a voluntary soft landings arrangement. In addition, contractor Willmott Dixon has implemented its Energy Synergy process, to measure and verify the school’s operational energy use by comparing metered data against monthly Passive House Planning Package (PHPP) targets, which has helped highlight some anomalies. For example, a building management system (BMS) demand signal to the GSHP stopped working after a software update to the BMS. This was picked up by a sudden increase in gas consumption.

The team’s perseverance has paid off; four years after the school opened, the latest sub-metered data shows energy consumption and generation is very close to the PHPP design targets and on track to achieve net zero energy (see Figure 1).

This pioneering school is finally living up to its A+ Energy Performance Certificate billing. With an energy use intensity of 42kWh.m^-2 per yr, Architype says the school exceeds RIBA’s 2030 operational targets and, with upfront embodied carbon with sequestration of 405kg CO₂e.m^-2, meets LETI’s 2020 embodied carbon targets. 

The building’s impressive green credentials are used to enrich the school curriculum and bolster environmental awareness among the pupils. This makes it a great example of how we can embed environmental design in our school buildings and inspire the next generation.

The post Case study: Passivhaus Plus Hackbridge Primary School appeared first on CIBSE Journal.

It won Project of the Year – Leisure at the 2024 CIBSE Building Performance Awards with judges impressed by its careful, low carbon design and application of technology.

What’s more, the performance data has been used as an exemplar case study by the UK Net Zero Carbon Buildings Standard, to help establish a best-practice benchmark for operational and embodied carbon for future leisure centre buildings.

To achieve this remarkable feat, building services engineers Max Fordham – working with architects FaulknerBrowns, the client and main contractor – have taken every design decision as an opportunity to minimise energy consumption further.

As such, the building incorporates a range of passive and active environmental technologies, including the extensive use of daylight and mixed-mode ventilation. In addition, heat is provided by air source heat pumps (ASHPs) incorporating load-shedding controls, while the complex is crowned by a giant biosolar roof that provides up to 20% of the building’s electricity needs.

The £57m sport centre’s low-energy design is a response to the university’s campus energy and sustainability masterplan. Developed by Max Fordham under a previous project, the masterplan includes a requirement for all new buildings to achieve Breeam Outstanding and a Display Energy Certificate (DEC) ‘A’ rating in operation.

Large rectangular rooflights supplement daylight in the pool area

To achieve DEC ‘A’, the design had to target a maximum EUI of 218kWh·m^-2 per year. Ambitiously, Max Fordham set out to meet this already challenging target without the use of fossil fuels. ‘When we started to develop the design in 2016, gas boilers were the standard solution, but we said “this building is not going to complete until 2022, when Grid carbon will be lower, so we should not be basing our design on fossil fuels”,’ says Mark Palmer, director and sports leader at Max Fordham. Opting for an all-electric solution would also ensure the building’s carbon emissions fall further as the Grid continues to decarbonise.

The university’s brief to the design team was for a sports centre with a 25m swimming pool, an eight-court sports hall, 175-station fitness suite, climbing wall, ski simulator, and fitness studios, along with offices and teaching spaces.

Palmer says the starting point in developing the building’s form was to separate the swimming pool from the ‘dry’ areas (the sports hall, fitness suite, and so on), so that the circulation space between can form an environmental buffer zone.

Unusually, the design places the sports hall on top of the ground-floor fitness suite and changing rooms. ‘One of the key decisions was to put the sports hall on the first floor, to ensure that it and the swimming pool could benefit from rooflights, to provide passive heating and daylight, which saves energy and is good for wellbeing,’ says Palmer.

One of the striking giant fans set into the ceiling in the gym. The fans have been designed to generate air movement to reduce the need to drive down the fitness suite air temperature

Flexibility is key to keeping the building’s footprint and embodied energy to a minimum. The swimming pool, for example, has a floating floor, to do away with the need for a learner pool; the squash courts are separated by a moveable partition to enable them to be converted into additional studio space; and the studio spaces incorporate a moveable partition that allow them to flex to accommodate a variety of class sizes and activities. The compact building’s high-performance envelope has been kept deliberately simple to avoid complex junctions and cold bridges.

In addition, the swimming pool envelope has been fortified with additional insulation, to deal with the higher air temperature and humidity in the space. Employing a simple, system-build envelope solution made it easier to build and, Palmer says, gave contractor Wates Construction ‘a fighting chance of delivering on the design airtightness and thermal performance in practice’.

The rooflights in the sports hall and swimming pool are designed to open. They are arranged in strips in the sports hall, strategically positioned between the badminton courts to allow daylight in while minimising the impact of glare on the players.

Max Fordham has eschewed natural ventilation for an innovative cooling and mechanical ventilation solution for the intensively used, 175-station fitness suite. Alongside a conventional fan coil cooling system, a series of large-diameter, high-volume, low-speed horizontal fans have been recessed into the ceiling, like the slowly spinning rotor blades on a series of upturned helicopters. These giant fans have been designed to generate air movement to reduce the need to drive down the fitness suite air temperature. The large fans are supplemented by 13 smaller fans concealed above the ceiling.

The conventional way to deliver comfort to a fitness suite is to lower the air temperature to help people lose heat. Sport England’s guidance, for example, suggests maintaining temperatures as low as 16°C-18°C. But Palmer says this can result in ‘very high energy use’ that often ‘fails to deliver occupant comfort’ because, when we are sedentary, radiation is the primary mechanism of heat exchange. As exercise intensity increases, however, convection and, eventually, the evaporation of sweat become the dominant modes of user heat loss. ‘If the air in a gym is cool, still and humid, your sweat is unable to evaporate to cool you down,’ Palmer explains.

For those undertaking high-intensity exercise, convective and evaporative transfer of body heat are increased significantly by air movement. ‘By creating air movement and controlling humidity, we are able to achieve much better levels of comfort at temperatures that are not as cold,’ Palmer adds. See ‘Fit for purpose’, CIBSE Journal October 2018 for more on this bit.ly/CJRav.

In addition to the giant fans, four-pipe fan coil units (FCUs) have been tucked out of sight above the suite’s slatted wood ceiling. The FCUs provide the space with heating and mechanical cooling. ‘The client was a bit nervous about the effectiveness of our giant fan solution, so the fan coil units have been sized to cool the space conventionally without the need to run the fans,’ says Palmer, who adds that the client need not have worried. ‘Everyone loves this solution: it’s striking to look at and it’s proven to be very effective.’

In addition to ensuring the university’s management and operations teams have a good understanding of the building and its systems, soft landings enabled the engineers to tweak the fan system once the fitness suite was fully operational. They estimate that increasing air movement in the fitness suite, as opposed to relying on a lower temperature setpoint, will result in a 10% reduction in energy use in peak summer conditions.

Heat for the building is supplied by five ASHPs via a low-temperature buffer vessel. To maximise ASHP efficiency, heating is at 45°C flow/40°C return, which, Palmer says, is ‘quite challenging when we need to heat the pool hall to 30°C. To operate the system at these low temperatures relies on high levels of heat recovery and a high-performance building envelope’. The solution also required non-standard fan coils, air handling unit coils and heat exchangers to exploit the low flow temperatures.

Reducing glare

Plots show the direct sun penetration at two points during the year. These simulations are conducted using a bespoke tool, Beam Tracer, created by Max Fordham to calculate specular reflections. Orange represents the direct sun transmitted through the glazing; pink is the reflection from the pool surface. As a result of the steep-angle reflections from direct sun through the top, lights remain at high level and do not enter the occupied zone, where they can cause glare. At low sun angles, some direct sun penetrates into the pool area and can cause glare to occupants. By carefully mapping the path of the sun, lifeguards can be positioned to avoid areas that experience glare from direct sun.

The ASHPs incorporate load-shedding controls to minimise peak heat loads and reduce their size, capital cost and embodied energy. Palmer says minimising heat loads, maximising heat recovery and using load shedding ‘has allowed us to squeeze the combined capacity of the heat pumps down to 525kW, around a quarter the capacity of boilers in a typical leisure centre’. This ensured the heat pump solution was space-efficient and economically viable.

The pool water heat exchanger, for example, has a heat demand of 500kW, which, under the usual control regime, would take up the full heat capacity of the ASHPs, leaving nothing for space and water heating. However, Palmer says the only time it needs to deliver this output is when it is heating the pool water up from cold.

For the majority of the time, the heat exchanger is only required to output about 50kW to maintain the water at a steady temperature – and because the pool water acts like a huge thermal battery, the system can wait until the demand for heat is lower. ‘We put a lot of work into ensuring the heat pumps are not oversized, because it would have been easy to think we needed four times as many heat pumps. But if you are in control of where the heat is going, it allows you to shed some of the loads,’ Palmer explains.

Two additional water source heat pumps are used to raise the water temperature from 45°C to 60°C to supply the hot water calorifiers.

In addition to the five heat pumps dedicated to heating, the sports centre has five, four-pipe heat pump chillers optimised to provide cooling, but which can also provide free heat to the building. These supply the FCUs with chilled water at 6°C/12°C. The units can simultaneously top up the thermal store using heat reclaimed from the cooling side. The heat generated by activity in the fitness suite and dance studios is captured and used to keep the pool warm and preheat hot water for the showers, explains Palmer. 

There is a heat recovery unit on the pool water filter backwash system, too. The backwash is used to clean the water filters. In addition, to maintain pool water quality, 30 litres of water is added to the pool per bather, with a corresponding amount removed. This water is used to flush the centre’s toilets.

Engineering the sports centre’s low-energy design was ‘the easy bit’, says Palmer, who adds that it is often the execution, rather than the design, that prevents schemes from achieving predicted energy performance. For Ravelin, Max Fordham was novated to Wates Construction under the two-stage design and build contract, and appointed by Wates Building Services to develop its installation and record drawings in Revit. The engineer also worked with Wates’ offsite manufacturer, Prism, to integrate prefabricated service modules and plant skids. ‘It meant we were able to take responsibility for the design from concept to installation,’ says Palmer.

Max Fordham also produced drawings for the client, with all CoBie asset information, as a full BIM project. Palmer is complimentary about how Wates Building Services (now SES) tackled the project. A two-stage procurement route ensured the contractor was able to price ‘every bit of kit specified, to avoid compromises with lower-efficiency alternatives’. Execution was also helped by the soft landings specification insisting that Wates appoint an independent commissioning manager (Banyards). Its task was no doubt helped by the building having more than 200 electricity and heat meters. ‘At completion, the building was properly and fully commissioned so that it performed well from the get-go,’ says Palmer.

Post-occupancy, the soft landings initiative requires Max Fordham to monitor the building and report each month on how the various spaces are performing – a task aided by the engineer having remote access to the BMS and meters.

There were also monthly meetings to gather client feedback. Palmer says: ‘If something was not working, it was raised at the meeting so that, by the next meeting, it had been resolved, which helped ensure the client never lost faith in the design and remained engaged in the low-energy strategy.’

A major challenge with sports buildings is the huge variation in occupancy throughout the day. In the evening, they are usually full and everything is running flat out, whereas, in the middle of the day, they are relatively empty. ‘M&E designs often only focus on meeting peak conditions and do not consider the other times when occupancy drops off,’ explains Palmer. ‘But you have some pretty powerful kit in this building, so you will waste a lot of energy if you don’t turn things down or off when occupancy drops.’

One issue raised post-occupancy was the level of local control that users should be given, particularly over the temperature of the fitness studios after complaints that these were either too hot or too cold.

Post-occupancy evaluation monitoring showed the rooms were performing as designed, with temperatures being maintained at 18°C, and CO₂ levels rising and falling, and the fresh air fans responding accordingly, depending on occupancy. After questioning users throughout the day, however, it became clear that when the spaces were used for high-intensity exercise classes, users found them to be too hot, whereas when they were used for a zen yoga class, for example, users were too cold. ‘We’ve now added a button to each studio to allow the temperature to be changed up or down a couple of degrees for an hour,’ says Palmer.

This approach has clearly worked, and highlights the benefits of a soft landings approach. Perhaps more impressive is that the scheme improved significantly on the original, challenging EUI target of 218kWh·m^-2 per year. 

The post Keeping fit with less energy: Ravelin Sports Centre appeared first on CIBSE Journal.

Retrofit has also become a companion to life sciences development, mainly because of a lack of new spaces that can handle the structural and services demands of life sciences buildings. There has also been a shift in demand for city-centre locations, driven by proximity to universities, hospitals and a skilled workforce.

Cambridge, Oxford and London, deemed as the life sciences’ ‘golden triangle’, are great examples of this. Both offices and retail have seen a decrease in demand, creating an opportunity to repurpose these spaces for science laboratories, where the demand remains strong. 

The retrofit challenge

All types of laboratories need supplementary ventilation and some form of fume extraction, and this can be a particular challenge for a retrofit in a built-up area.

The higher ventilation rates required to extract fumes from laboratories means risers need to be larger than those for offices to accommodate more intensive services, and ceiling void space needs to increase by 50cm to make room for larger duct work. Existing buildings that already have high floor-to-floor space, such as shopping centres, are more easily retrofitted as laboratories.

In the past, a lot of buildings were thought to be structurally unsuitable, as external vibrations hindered the ability for optical microscopes in labs to achieve stable images. However, recent technological advancements such as active vibration damping, which operates in a similar way to noise-cancelling headphones, have helped overcome such structural issues.

Specification of ventilation starts with a suitable selection of fume cupboards and biosafety cabinets, for the specific application and chemicals that are anticipated to be used. Ducted fume hoods are typically the most effective for removing fumes.

The placement of hoods must be carefully considered to capture contaminants effectively, by ensuring that there are no obstructions blocking airflow to the hood. Computational fluid dynamics (CFD) modelling is often needed to validate the design before implementation. 

A minimum air change rate must be achieved for safety purposes in laboratories and this is typically three times more than conventional office buildings, requiring larger HVAC facilities. 

It is important to consider where the fumes are discharged and their proximity to other air intakes and receptors.

Conventionally, air intakes must be separated from discharges by at least 10 metres, and fumes are discharged vertically at least three metres above other parts of the building. However, for city centres with an abundance of developments, more detailed assessments are often required.

When direct, ducted systems cannot be incorporated, recirculating systems with activated charcoal air filters and scrubbers can be considered, although these are expensive alternatives.

Higher ventilation rates and fume-extraction systems will have a significant impact on a building’s energy use, so it is essential that buildings services pay particular attention to energy efficiency.

As a first step, it is important to work with the scientists who will be occupying the buildings in the design stages, to optimise the parameters and the airflow design, and prevent overdesign. 

Where possible, spaces should be lab-enabled, rather than fully fitted-out. This will provide end users with an adaptable blank template they can fit-out however they want. This is more attractive than receiving a fully fitted-out space that may not meet specific requirements and could put occupiers off at due diligence stage, or lead to expensive refit financial and carbon costs.

Modulating the airflow to match actual demand reduces energy consumption during low-activity periods, while still providing adequate ventilation when needed.

Variable air volume flowrate systems and demand-control ventilation can adjust the ventilation rates based on real-time occupancy and contaminant levels. Implementing scheduling controls can also optimise ventilation operation based on occupancy patterns and laboratory usage schedules.

Rob van Zyl

Natural ventilation can be used in certain situations. There are other considerations such as prioritising recirculation over full ventilation by using activated charcoal filters or liquid scrubbing to wash the air as it passes through. Heat recovery systems must also be implemented wherever practical, to capture and reuse heat or coolness from exhaust air to precondition incoming fresh air.

Typically, the requirement for safe removal of fumes is to discharge fumes at least three metres above the highest point of buildings, and this means having tall and unsightly stacks.

In the UK, planning regulations impose restrictions on the height of stacks and exhaust vents as part of the overall planning permission process. This is primarily to address concerns of air pollution, visual impact, and potential adverse effects on the environment and neighbouring properties.

Planning authorities need evidence to show that vertical stacks are tall enough to adequately control the dispersion of pollutants and they will want to see how the visual impact of stacks on the surrounding landscape have been considered.

Stack heights need to be specified to minimise impact on air quality. They will be based on factors such as the type of emissions, local air quality standards, and the proximity of sensitive receptors, such as residential areas, schools, or hospitals.

The speed at which air is discharged from a ventilation system – the efflux velocity – can determine stack height. By increasing the velocity of vertical discharge, fumes can be pushed higher and the stack height reduced. CFD modelling can be used to predict whether or not the concentration of released fumes will exceed the required parameters of the nearby receptors. It should be borne in mind that higher efflux velocities require more energy. 

The importance of heat recovery

As there is a requirement for labs to have a lot of air circulating in the building, it is important to recover as much of its heat as possible. However, effectively capturing and using waste heat can be difficult in practice. In some cases, the temperature difference may be insufficient to extract heat efficiently, limiting the feasibility and effectiveness of heat recovery.

Integrating heat recovery systems can be difficult, as it will introduce pressure drops. It can also create foul air that can be corrosive, which means the ductwork must be made with corrosion-resistant materials that will not be damaged by this. 

Science buildings are one of the sectors being considered by the Net Zero Carbon Buildings Standard (NZCBS). Simon Wyatt, sustainability partner at Cundall, is leading the NZCBS¹ sector group and is collaborating with market leaders to create assessment frameworks for buildings in the sector. It is still early days for the sector, and there is a lot more data that is needed before benchmarking of life sciences buildings is taken seriously.

About the author:
Rob Van Zyl is a management board partner at Cundall

References:

1. UK Net Zero Carbon Buildings Standard www.nzcbuildings.co.uk

The post Science in the city: the challenge of retrofitting labs appeared first on CIBSE Journal.

It served as the city’s seat of governance for more than 600 years, but when York City Council relocated, it wanted to refurbish the historic complex and turn it into a digital hub for the 21st century.

Together, architect Burrell Foley Fischer and SGA Consulting set out to deliver the council’s vision.

The interior of the 15th- century York Guildhall

Alongside the creation of the digital hub, the project involved the refurbishment of the listed elements of the scheme to improve accessibility, occupant comfort and energy efficiency. It also included a new office extension and riverfront restaurant at the side of the complex.

The scheme’s numerous listed elements made for an extremely challenging refurbishment. Except for the listed cast iron radiators in the Victorian council chamber, all of the existing building services had to be replaced, as they were long past their prime. ‘We started by asking what interventions we could make to the listed buildings and then set about working out how to deliver these in the best possible way,’ says Bart Stevens, a director of SGA Consulting.

some materials were transported by river

The building’s location, adjacent to the River Ouse, made a river source heat pump (RSHP) the obvious solution to heat and cool the building. ‘The first time I went to the site, I took one look at the river and said “of course we’ve got to use this”,’ recalls Stevens.

Permission to use the river was obtained from the Environment Agency and the Canal & River Trust, and an unobtrusive route for the abstraction and discharge pipework was devised from the basement plantroom to the river.

Under the new scheme, 110kW of simultaneous heating and cooling is provided by a two-circuit, reverse-cycle RSHP. To optimise its efficiency, the heating circuit runs at 50^oC flow/45^oC return, while cooling is at 6^oC flow/12^oC return. The RSHP is also designed to recover heat if areas of the building require simultaneous heating and cooling.

Pipes taking water from the Ouse to the river source heat pump

A pragmatic fabric-first approach was adopted by SGA Consulting in developing the servicing strategy. Using the heat pump to service the new office extension and restaurant was relatively straightforward, because its fabric thermal performance exceeded Building Regulations minimum. However, the listed status of many existing elements and spaces meant opportunities to improve fabric thermal performance were limited. This had a major impact on how and where the heat pump-derived heat could be used.

The office extension and riverfront restaurant

The lower temperature of the heat pump heating circuit made it ideal as a heat source for underfloor heating, because the large floor area helps compensate for the lower temperature of the emitter. The heat pump is also used to supply heat to fan coil units (FCUs) in some of the office spaces. These incorporate oversized heating coils to compensate for the circuit’s lower flow temperatures.

Operating in reverse mode, the heat pump uses river water, extracted at up to 22^oC and returned at 25^oC, to also provide chilled water to the FCUs in south-facing river frontage rooms. ‘These rooms required cooling as well as heating, so we were justified in replacing the existing radiators with modern FCUs in these rooms,’ explains Stevens. 

Reinstating Victorian natural ventilation

SGA Consulting has resurrected the original Victorian ventilation system to help alleviate stuffiness and overheating in the Grade II*-listed council chamber.

The original building services proposal incorporated a series of FCUs to keep the council chamber comfortable. The units were to be placed outside the chamber and holes knocked through the wall to enable the units to circulate air. Historic England was not keen on the modifications, so an alternative solution had to be devised.

‘I said “I bet the Victorians had a way of ventilating the room”,’ recalls SGA Consulting’s Stevens. Low-level ventilation inlets had been identified in the external walls, hidden behind the cast iron radiators which also provide preheating to air entering the chamber. ‘After hunting around, we managed to find some holes in the ceiling, concealed behind rose-shaped bosses, which allowed the warmed air to exit the chamber and enter the roof space,’ says Stevens. In the roof, the ventilation system was originally linked into the flues from the coal-fired boilers using wooden ductwork . The system exploited the pressure differential caused by the upward flow of air from the boiler flues to induce airflow through the council chamber.

The original council chamber ventilation system

SGA Consulting set out to reinstate the original ventilation system, to enhance the airflow without any discernible visual impact in the council chamber. The coal-fired boilers are long gone, but the system still uses the original boiler flue. Because of fire regulations, the Venturi effect from the boiler flue had to be abandoned, so the airflow is now enhanced through the addition of a small axial flow fan.

To further control airflow in the council chamber, motorised dampers (controlled on CO₂ and temperature) have been added to the low-level intakes behind the radiators. Should they so wish, councillors also have the option of opening windows.

SGA Consulting has also managed to hide four cooling-only FCUs beneath raised daises in the council chamber. This helps keep the space comfortable when the council is in session and the room is full of people. The consultant has also resurrected the original Victorian ventilation system in the chamber to further improve comfort.

A major benefit of using a RSHP to provide cooling was that it removed the need for an external air cooled condenser, which would have been noisy and visually obtrusive in this overlooked, congested and historic part of York.

The RSHP is housed on a plinth in the potentially flood-susceptible basement plantroom.

Alongside the electric RSHP, the scheme also includes three new gas-fired boilers. These supply a conventional low-pressure hot water heating circuit at 80^oC flow/70^oC return to furnish the cast iron radiator circuit in the Victorian parts of the building, along with two domestic hot water calorifiers that serve the new kitchen and toilet blocks. The boilers also provide back-up heat to the heat pump circuit, should the heat pump fail.

‘We used the heat pump in all of the spaces where we could make it work, but the heat losses are so great in the Victorian areas, and the floor areas fixed, so we had to reuse existing cast iron radiators and gas boilers to provide sufficient heat,’ explains Stevens.

The new extension to York Guildhall

Heat losses in the 15th-century Guildhall were also particularly high. The building’s Grade I listing meant that it was too difficult to enhance the thermal performance of the solid stone walls and there were insufficient funds to add secondary glazing to the windows. The team was, however, able to hide additional insulation in the roof as part of the lead-replacement works.

Bomb damage during World War II meant that the roof, floor, and some upper walls of the Guildhall had either been rebuilt or replaced, so English Heritage permitted underfloor heating to be installed in the 7m-high space. Even so, heat losses were so great that the heat pump-supplied underfloor heat system alone was insufficient to keep the space comfortable. ‘The heat losses were too high and we were very limited as to the interventions we could make,’ says Stevens.

Boilers are used on very cold days because of high heat losses in the historic buildings

SGA Consulting’s solution was to supplement the underfloor heating with trench heaters concealed within the floor and connected to the higher-temperature gas-fired boiler circuit, for use on cold winter days.

‘When the outside temperature drops below 5^oC, the trench heaters turn on,’ Stevens explains. As a consequence, trench heating will only deliver 12% of the Guildhall’s annual heating demand, with the rest provided by the heat pump circuit. ‘This type of mixed use shows how heat pumps can be used to provide heating to old buildings where the rate of heat loss would be too high otherwise,’ says Stevens.

After the scheme’s completion in 2022, SGA Consulting followed a soft landings regime for two years, to optimise performance of the building services. Lessons learned include:

• Keeping the Guildhall underfloor heating off on cool summer days because of the long time lag in delivering heat
• Turning off the heat to the domestic hot-water systems over weekends when appropriate
• Reminding the client of the two-speed control for kitchen ventilation.

The strategy to re-use a centuries-old building, revitalising it for use for future generations, achieved significant savings on embodied carbon emissions. Equally importantly, the project succeeded in securing the future of the Guildhall complex; the University of York is taking a long-term lease on the historic buildings to create a business hub for spin-off firms from the university. This will contribute to the city’s future and is proof that historic buildings can be refurbished and remodelled to meet contemporary needs.

SGA Consulting’s approach to the project certainly impressed the judges at this year’s CIBSE Building Performance Awards, where the project won a host of awards, including Building Performance Champion.

The judges said of the scheme: ‘With the challenges we face in renovating millions of existing buildings, the York Guildhall project shows what can be achieved to deliver sustainable building refurbishment, minimise embodied carbon and deliver such a project with the most difficult site-access conditions’. 

The post Bridging the gap: the 2024 CIBSE Building Performance Champion appeared first on CIBSE Journal.

Despite this industry-wide push, however – and engineering calculations that indicate usage will be lower – consultants and contractors are hesitant to trust the efficiency of all-electric systems. They are also inexperienced in determining accurately the peak electrical loadings for all-electric buildings.

They do not understand, or are not ready to believe in, the efficiency of these recent technologies. This is partly because they are not willing to trust the calculations made in the design stages and tend to overdesign margins. This is a significant barrier to widespread adoption of all-electric designs – not just in schools, but in all types of buildings.

As the first wave of all-electric schools start to reach completion, it is up to building services engineers to bridge the gap and help educate the industry, so we all have confidence in the calculations. We need to look at how these first all-electric schools perform in operation by regularly measuring and reporting the performance.

This is not something we have historically been good at as an industry, and it requires a step change to get everyone on the same page. Once you start looking at these schools, numbers are clear, and they go a long way to helping understand actual demands and usage. They can then be fed back into calculations in the design stages of future schemes.

Recently, Cundall was part of the project team that completed West Coventry Academy, a 12,000m² secondary school with a sports block and swimming pool. Part of the DfE’s School Rebuilding Programme and Net Zero Carbon in Operation Pathfinder scheme, it was handed over in September 2023, and is all-electric in operation except for a small gas boiler that serves the pool’s water-heating system. The school has air source heat pumps (ASHPs) for heating and kitchen hot water, and direct electric hot water for everything else. It also has LED lighting and controls, and a small photovoltaic (PV) array (100% PV array was not specified in the brief, but there is room to add this in the future).

The building has a well-insulated and airtight façade, featuring Innovare structural insulated panels and high-performance glazing. The design peak heating load is 280kW, just 23W/m². Ventilation is hybrid, incorporating mechanical ventilation units with heat recovery for all occupied spaces for tempered fresh air in winter, and natural cross-ventilation via circulation atria roof turrets for summertime ventilation. The only cooling is to the server room, and some classrooms have exposed ceiling fans to aid thermal comfort.

The school had taken part in the DfE’s ‘pathfinder scheme’ and, in 2021, had employed the then new DfE Output Specifications and technical annexes that had not been put into practice on any scheme previously, and had continued as a test location for these new specifications. When we designed West Coventry Academy, we called on our experience with a previous Priority School Building Programme project, finished in 2018, that we knew had resulted in a maximum in-use electrical demand of just 276kVA (17.2W/m²).

Many did not believe we had achieved such low figures, but we had the electric bills and meter readings to validate this over several years. With this in mind, we designed West Coventry Academy to have a maximum in-use electrical demand of 550kVA (48.2W/m²), and we were confident our design would generate results similar to previously acheived. When the design and build subcontractor took over at RIBA Stage 4, however, they were not so confident in our calculations and an 800kVA supply was installed.

Six months on from West Coventry Academy being handed over, the school has experienced a winter that included a particularly icy -8°C cold snap, on 18 January 2024. The Cundall team visited the site a few weeks later to gather data and discovered that the maximum demand recorded was just 398kVA (33.7W/m²) – lower than even we had predicted for maximum energy demand, and far, far less than the 800kVA supply that had been installed.

This is a clear demonstration of the efficiency of all-electric designs, even in extreme conditions. It also highlights the potential cost implications of overdesigning maximum electrical demand and the associated infrastructure and low-voltage supplies.

It is a habit that we, as an industry, have acquired after years of designing low-efficiency, poorly insulated gas-fired schools. This overdesign not only adds cost, but also carbon – in construction and for the school itself, which, potentially, is left with a lifetime legacy of higher standing charges for a capacity it will not use.

On a lot of new or replacement schools, this can lead to expensive substation upgrades and high-voltage network reinforcement, which, again, may be unnecessary for the school in the long term.

Another reason the industry tends to overdesign schools is that the BSRIA BG9 2011 design guide suggested an electrical services load of 35W.m^-2 for naturally ventilated schools (or 50W.m^-2 for mechanically ventilated ones), and this assumes that heating and DHWS energy is fed by gas or other non-electric sources. The guidelines are based on 12-year-old data from gas-fired heating and hot water, and haven’t been updated to account for all-electric schools. (BG 9 has now been superseded by BG 84/2024 ‘Space and Weight Allowances’ ).

Typically, total connected loads are established based on good design data, and percentage-based diversity factors are then applied to equipment, ASHPs, domestic hot water systems, and other loads. These percentage based diversities are no longer appropriate.

In recent years, we have seen electrical infrastructure designs presented of typically 120W/m² – nearly four times the maximum demand recorded at West Coventry Academy on the coldest day of the winter. Some designs are even higher, and this is clearly based on guesswork, not empirical data or good practice.

We cannot really blame designers for this; the guidelines have not kept up with the current rate of change when it comes to best practice on how we design our schools.

To counteract this problem, Cundall has established a school daily demand profile tool (see graph, left). The peak loads have been taken from actual meter readings of all-electric schools that we have designed. The daily data around these peaks is based on metered annual consumption data, with some adjustments applied depending on school specific facilities for design and technology or computing. BIN weather data is employed to simulate annual profiles based on the available data. When a full set of seasonal meter readings are available they will be used to improve the model.

West Coventry Academy has air source heat pumps for heating and kitchen hot water

The central premise is that the sum of all hourly and daily loads can be used as a check and equated back to an annual load. We must design schools to achieve specific DfE energy use intensity targets, expressed as kW/annum/m², and, clearly, if these are exceeded in this check sum, you have overestimated a particular load.

This data can be extrapolated and used on any other school type to assist with future design estimates, and is a far more accurate way of calculating maximum in-use electrical demand until the guidelines catch up.

My hope is that we can speed up that process and replace the simplistic rules of thumb by feeding the irrefutable data we have collected already into upcoming design specifications.

In the meantime, the key for everyone in the industry, but especially building services engineers, is to keep measuring and reporting regularly on the in-use operational performance of the buildings we design. 

• Peter Hazzard is a partner and schools sector lead at Cundall

The post Essential lessons from electric schools appeared first on CIBSE Journal.

The building is made up of three spaces. The main event space is the 21-metre high warehouse, which can be split into two. It is complemented by the hall, a 1,603-seat auditorium with a flexible stage, while a seven-storey tower at the back of the warehouse provides green rooms, dressing rooms and office space.

The building’s façades, of concrete and corrugated metal, contrast with the refurbished brick warehouses and newly built flats, offices, and television studios that make up the new St John’s neighbourhood.

Building services and lighting design had the challenge of responding to the multiple uses of the building while maintaining an industrial aesthetic.

Gas boilers are used for heating currently, but the building is designed to connect into the future St John’s heat network. The hall and warehouse are air cooled and heated, while the tower and social rooms’ loads are met with local emitters. Chillers provide cooling.

Close collaboration between BDP’s electrical, mechanical, lighting and digital engineers was essential because of the complex nature of the internal building geometry, and a BIM model was created to coordinate services.

The BIM model showing the three building elements

The lighting team worked closely with architect OMA and interior designer Brinkworth to coordinate lighting concepts. The result is a combination of general, architectural, experiential, complex emergency, and technical theatrical lighting systems, threaded through the internal building geometry. Three bespoke luminaire types that worked with the contemporary façade design were developed with Stoane Lighting and Zumtobel. In total, 164 luminaire types were used throughout the building.

The energy model demanded >100lm ·W^-1, a significantly higher requirement than that in Part L, which was 60lm ·W^-1 at the time of design in 2018; in the 2021 revision it is 95lm·W^-1. Illumination criteria for general and emergency lighting was determined using the Technical standards for places of entertainment 2015 – The association of British theatre technicians in combination with the usual CIBSE and British Standards. 

The warehouse has capacity for up to 5,000 people standing, and can be divided by a movable, full-height acoustic wall. The hall has a flexible stage that can house an audience of up to 1,600 seated or 2,000 standing. The warehouse and the hall can work together, allowing the stage to extend to a depth of 45 metres. The lighting includes house lighting, management lighting, high output working light, technical space task lighting, and back-of-house blue lighting.

House lighting was provided by ETC ArcSystem luminaire types. These warm white digital multiplex (DMX) fittings mounted to the technical grid allow super low-end DMX dimming to achieve 0.2 lux management light levels. High-output working light illumination of >600 lux was provided by 58,000lm downlights from Glamox. 

In areas where people are working without windows, a 5,000K correlated colour temperature (CCT) has been selected to increase the perception of brightness. Technical spaces use a combination of >500 lux white-light illumination and a blue lighting system for access during a performance. 

Underneath the auditorium

The hall is a traditional raked theatre with removable seating. A range of luminaire types was integrated into the interior architecture to celebrate and delineate the internal geometry, and contribute to house lighting levels. Details include a balcony shadow gap, in-floor uplights, skirt detailing, and uplighting to the soffit from the technical grid edge. A bespoke luminaire was developed to illuminate stair treads. The restricted floor buildup of the auditorium did not allow for a more traditional step-tread lighting solution, so a free-standing, floor-mounted step light was developed that could be installed in the voids below seating.

The warehouse is designed to be a blank canvas. Vertical DMX colour-change linear luminaires around the perimeter can support events with a full-scale lit feature. The general and emergency lighting arrangement allows for cellularisation of the space for set building and isolated space uses.

The tower has multi-level mixed-use spaces connected to the warehouse and includes offices for Manchester International Festival, the green room, and dressing rooms. Most of these spaces have no ceilings and exposed services, so a trunking system was used to minimise ‘visual clutter’. The trunking houses pre-wired power and data, reducing the requirement for secondary containment, making it time- and cost-effective. A range of luminaire types can be inserted, including standalone emergency modules.

Danny Boyle’s version of The Matrix launched the venue last autumn

The main foyer has multiple uses, which is reflected by the lighting. The design responds to the brick arches of the 19th-century railway line that forms part of the foyer. A mixture of adjustable cool-white wide-beam and warm-white narrow-beam track spots are used to create day and evening scenes, combined with uplighting on brick facades.

Integral lighting was used for bar fronts and shelving, and lighting was integrated into the stair handrails, providing localised illumination to the steps, reducing shadowing, and adding a sense of drama. The handrails also provide high-risk emergency lighting. That the building contains very few windows has been used to its advantage by the team, which has harnessed the transformative quality of light to create a variety of scenes and evoke different atmospheres for day and night. 

Outside the building footprint, in the public realm, an undercroft is illuminated with levels suitable for pedestrians and cyclists, ranging from 15 lux to 250 lux, appropriate for daytime and night-time use. 

The design of the services prioritises flexibility, responding to each individual performance and accommodating shows with diverse sets. 

Electrical infrastructure

The electrical infrastructure divides into two systems: house services and a dedicated performance system. This segregation prevents any interference, and handles uneven load distribution. A network of busbars and tap-offs feeds into multi-outlet power panels, complemented by fixed outlets distributed throughout.

A room in the tower

The building boasts an extensive stage lighting and audio visual (SLAV) system, interconnecting outlet panels to form a robust network. A centralised control system oversees this network, employing various AV and data cabling types to match the different shows and setups. 

Strategically placed outlets and power panels in every part of the performance electrical system offer flexibility for main and breakout productions. This, combined with SLAV outlet panels, allows for dynamic show configurations. An advanced performance lighting control system, connected to a central hub, governs performance and house lighting, offering flexible control.

Ventilation and acoustics

A top-down supply ventilation strategy, using swirl jet diffusers, was adopted for the theatre and warehouse to maintain flexibility without introducing physical constraints. To address potential noise challenges, careful diffuser selection was crucial.

Rather than applying a uniform building service noise criterion, specific criteria were established for each event scenario, allowing for more relaxed standards where higher building service noise levels were acceptable. This flexibility matched the requirement for events that needed increased airflow rates, such as high-capacity concerts.

A section view showing the interconnection between the Hall and the Warehouse

Building physics modelling was employed to manage potential noise concerns during heating. This verified that when the hall and warehouse were pre-heated before a show (when higher service noise levels were acceptable) temperatures could be maintained during performances. 

Aviva Studios is an exciting new addition to Manchester’s vibrant cultural scene and the innovative building services engineering and bespoke design allow the operator to create a myriad of performance spaces that put visiting artists in the best possible light. 

• Steve Merridew is a building services engineering director and Nick Meddows is senior lighting designer at BDP

The post Setting the scene: Manchester’s new arts venue Aviva Studios appeared first on CIBSE Journal.

Many traditional roof-construction techniques consist simply of a roofing material over a structure that allows rainwater to collect and run off the side of the building into the landscaping. This traditional technique is still common in countries such as Japan, where, often, less is more in architecture, and the built environment strives for minimal impact on the natural watercourse.

Through early advancement of building techniques, some countries adopted gutters and downpipes in the early 19^th century. These were used to convey roof rainwater in a controlled manner to points around the building. Gutters and downpipes can be used around the whole roof perimeter, or local to building openings and awnings where free-draining rainwater might cause a nuisance. Today, gutters and downpipes are necessary to collect rainwater in a central point for harvesting and re-use – let’s park this thought for now. 

In Australia, our National Construction Code provides the overarching requirement for building rainwater designs to keep water out of the building during a one-in-20-year and one-in-100-year storm. It then refers us to AS3500.3 Plumbing and drainage – Stormwater drainage for a guide to achieving this overarching requirement; by following this code, you may produce a ‘deemed to satisfy’ design. 

AS3500.3 is not a one-size-fits-all approach to every building. For example, the charts within this standard limit the flow to any single downpipe to 16l/s. In some instances, this is not appropriate for a building, so the hydraulic design may choose a ‘performance-based pathway’ for compliance using other recognised standards or calculation methods.

This same performance-based approach can be applied to allow a roof to drain freely, like the traditional Japanese roof structure. A canopy at the Art Gallery of New South Wales Sydney Modern Project is one example. The reasons for doing this may be an architectural vision, cost benefits, materials reduction, or a landscape strategy to return rainwater directly to the earth.

When looking to adopt this design philosophy, there are a few considerations that need to be addressed – all of which go back to our overarching requirement to keep water out of the building.

Wind-driven rain and water ingress

Wind has a huge influence on the path of travel for a drop of rain. The dynamic relationship between wind, rain and buildings is complex and challenging to predict without detailed site-specific wind analysis by a
wind engineer.

In most cases of building design, wind and rain are intensely affected by the immediate surroundings and topography, and their estimation is limited to environmental data available at that location. 

Traditional Japanese building where rain runs off the roof onto the landscape

Despite myriad research into wind-driven rain within the built environment, its behaviour is still ambiguous. Also without a body of sound equations available to apply to roof and façade drainage designs, understanding rain behaviour will be on a case-by-case basis. 

We know the behaviour is influenced by the local wind climate, the velocity of rainwater as it leaves the roof, height of the roof and distance before a water stream separates into droplets, rain droplet size, and intensity.

Wind experts suggest the angle between the roof and the maximally deflected stream of ejected water is 30°. Using simple trigonometry, we can then calculate the horizontal deflection at ground level. 

This can help reduce the risk of wind-driven rainwater ingress. Door and airlock configurations and threshold façade drains should also be considered. Where there is a risk of water entering a critical space, a wind engineer should be consulted.

Drip-line effects

Disturbance of hardscaping or landscaping below the drip line could be damaging to a building’s reputation or how it is viewed
upon approach. It is not uncommon to see building entry-way awnings with a free-draining rainwater approach result in unsightly staining of tiled finishes below the drip line. 

Similarly, concentrated flows directed into soft landscaping can result in erosion and disruption of landscaping over time. To overcome this issue, hard landscaping, alternative tile finishes, rockeries, or even drainage features could be considered.

Overcoming rainwater contamination

As water scarcity becomes more of an issue across the globe, engineers are increasingly including water harvesting – and the reuse of black water, grey water and, more commonly, rainwater – in designs. 

Traditionally, harvesting groundwater for local reuse on site has been ignored because of increased levels of organic contaminants risking bacteria growth within stored water supplies, and tannins leaching into the groundwater as it passes through soil and decaying vegetation. This gives the collected water an earthy odour and brownish colour, which can cause staining on fixtures, fittings and fabrics.

Overcoming these challenges is straightforward with filtration, but comes with an increased cost. The actual contamination risk needs to be known, as does the water-quality requirement at the point of use. 

If the harvested water is being used for underground drip landscape irrigation, the risk is low and particle filtration may suffice. 

However, if the water is for toilets and urinal flushing, where occupants and building owners are at risk of being exposed to waterborne droplets created during flushing, a more robust filtration configuration of particle filtration, UV disinfection or reverse osmosis may be considered. This would also eliminate the risk of staining of fixtures.

With the right approach, a free-draining roof scheme can be an elegant solution, reducing the impact of visible pipework and gutters, and accentuating roof lines and views of the building.

When called on as engineers, we should support architectural expression rather than hide it. Often, the challenges can present opportunities for alternative performance-based design solutions that allow engineers to show their true value.

• Jake Cherniayeff is Arup’s hydraulic and fire services leader, Australasia

The post Going with the flow: how improved design can lead to better roof drainage appeared first on CIBSE Journal.

Though many of our museums and galleries were designed to be lit primarily, or even exclusively, with daylight, those openings have often been blocked up over the years because of concerns over conservation and light damage. The unintended effect of these measures has been to lessen the connection with the outside, making orientation more difficult and depriving occupants of the wider benefits of natural light. 

Max Fordham is routinely tasked with safely reintroducing daylight into existing galleries and museums, as well as ensuring that we make the best use of natural light and views in our new-build projects. The challenge is to create beautifully day-lit spaces that maintain the standards of conservation needed for the utmost care of precious exhibits.  

Our constantly changing climate means daylight levels are inconsistent and we need to aggregate them over a long period of time to understand them properly. The technology needed to undertake these kinds of virtual studies, as well as to validate them through long-term onsite monitoring, has only been developed recently, and is allowing us to use daylight much more extensively. 

A good example of this is at the Hayward Gallery on London’s South Bank, where we were able to restore the iconic roof pyramids and return daylight to the galleries after an absence of 30 years. 

Advanced analysis techniques now allow us to understand more precisely the distribution of natural and artificial lighting in every space, and we are able to give curators a much larger display area without increasing the size of the building. This, in turn, lessens our reliance on energy-intensive conditioning systems and allows us to greatly reduce the embodied carbon emissions of museum projects, through reuse and restoration, rather than demolition and rebuilding.

In the Queen’s Diamond Jubilee Galleries at Westminster Abbey, our detailed daylight modelling enabled the exhibits to be carefully placed around the path of incoming daylight. They filled previously unused spaces at balcony level and created a whole new gallery without the need for an extension.

Max Fordham built on this experience and created a digital twin of the National Portrait Gallery during its recent renovation, simulating the contributions of sunlight and skylight to the internal spaces over the course of a test year, using existing measured and future climate data. To achieve this, we generated 8,000 simulations, each requiring the accurate tracing of more than 200 million rays of light. 

The design team then used the lighting model to plan exhibitions, design the artificial lighting, and test different approaches to window and rooflight treatments. The outcome has been a gallery reconnected with its surroundings, where visitors and staff can easily find their way about, and where the subtle changes in natural light over the course of each day offer a uniquely healthy and stimulating visual environment. 

We also used the digital twin to repurpose the redundant system of rotating sun louvres – installed on the roof at the turn of the millennium – into new fixed shades. This eliminated the need to power them all day or to replace them as they fail. All the site team had to do was rotate each of the louvres to their perfect pitch to allow the natural light in the galleries to vary in close communion with the outside world, while the artworks remain safely within current conservation limits.

A well day-lit gallery needs a complementary system of artificial lighting, bringing flexibility, changes in mood, and the ability to focus light onto exhibits, as well as the facility to use the institutions outside daylight hours. 

The key trends in exhibition lighting at present follow those of the wider construction industry, with an increasing emphasis on human wellbeing, inclusivity and sustainability. In lighting terms, this means ensuring that the installation addresses the specific needs of different groups, such as: older people, who require more light to see clearly; those on the autism spectrum, who can be more sensitive to glare and for whom adaptable lighting with breakout spaces can offer respite; and people with dementia, who can be helped by designing away dark corners and sharp contrast within the galleries. Our aim is to achieve these goals using the minimum amount of energy and resources.

A thoughtfully designed artificial lighting installation can support the efforts of curators who are trying to create a more inclusive narrative in their museums and galleries. This means providing lighting for a much wider range of objects in a single space, often including those that may reveal a broader section of our history, but which are more sensitive to light – such as old photographs and letters. 

The recently reopened National Portrait Gallery is a good example of this approach. Flexible, Bluetooth-controlled lighting structures enabled us to carefully position objects with different conservation needs in the same space, while still allowing views out and an overall feeling of brightness and clarity.

Advances in lighting controls and colour management mean we are able to design whole systems that can be adjusted for tone and colour temperature, allowing us to tune the lighting to each object so that they can be revealed to visitors in the best way possible.  

At the Southbank Centre in London, all the lighting is digital multiplex (DMX) controlled and red, green, blue, white (RGBW) enabled, so each space can be put to many different uses, such as live music in the foyers and club nights in the café.

In summary, museums and galleries can benefit greatly from the judicious use of daylight, especially when coupled with a dynamic and flexible artificial lighting scheme. By combining advanced simulation techniques with the latest technologies in lighting and glazing, we can deliver cultural projects that are healthier, more engaging, more inclusive, and lower in both embodied and operational carbon. 

About the author
Nick Cramp is a partner director of Light + Air at Max Fordham

The post Lighting up the gallery: daylighting in arts institutions appeared first on CIBSE Journal.

Measuring 64m long and 4m wide, and with 12 roof modules of varying heights, the stainless steel structure houses toilets and seating. The elegant, simple geometry of the design is unashamedly contemporary, but created to complement, rather than compete with, its surroundings. 

‘The double-curved roof construction has a horizontal roof line, which is a reference to the fjord, and an undulating roof line, which is a reference to the mountainsides,’ says Code Arkitektur. ‘When you rest under the vaults, you experience different sections of the landscape space, together with the changing reflections of the light in the steel.’

The rest stop is designed to both integrate and contrast with nature

The lit effect at night follows similar principles. ‘We set out to create a visible landmark after dark, in tune with the local landscape,’ explains Light Bureau’s UK design director, Arve Olsen. ‘Our lighting design is inspired by the location and the surrounding nature: the cool moonlight that illuminates the mountain tops and the nearby glacier, in contrast to the warm, human light.’

The roof and wall surfaces are shaped by hand and welded together from 6mm-thick steel plates. The steel walls are kept free of equipment and all technical installations are cast into the concrete deck. Cool and warm light is used to create a clear distinction between the indoor and outdoor spaces, the columns, in cool light, framing the view towards the toilet, in warm light. 

‘The cool light of the outer walls is designed to contrast with the warm interior,’ says Olsen. ‘As lighting designers, we aimed to accentuate the sculptural shape through an interplay of light, darkness and contrast in the colour temperature.’

The lighting of the ceiling surface is asymmetrically designed to give two different visual impressions depending on the direction from which it is viewed, while the reflections in the steel create a play of light. ‘The intensity of the light on the steel wall had to be experienced visually,’ explains Olsen. ‘Therefore, tests were crucial, to ensure good detailing and to see the actual effects of light.’

The cool light of the exterior walls contrasts with the warm interior light

The luminaires are discreetly moulded into the deck and integrated into door frames. To achieve functional lighting in the toilets, each cubicle is equipped with a special bollard, in steel and acrylic – produced by the metal workshop Størksen in collaboration with UK company Stoane Lighting – which acts as a floor lamp and provides a soft light in the room.

The light from the bollard balances with the light in the door frame, which is made of steel and hardened glass. The lighting is controlled by sunrise and sunset times, as well as sensors in the lock box on the toilet doors, so that the light intensity increases when the toilet is in use. ‘This limits energy consumption and unnecessary lighting when the rest stop is not in active use, and lets the fjord and mountains set the stage,’ says Olsen.

The light levels are generally dimmed to limit the impact on the surroundings and local ecology, and to minimise glare, preserving the view from the rest stop. The remaining architectural lighting is balanced against the dimly lit roof – less than 40W is used to illuminate the 50m-long roofline.

The undulating roofline is a nod to the surrounding mountains

In fact, the scheme is as much about what is not lit as what is. The road that leads to the rest stop is not illuminated and the lighting of the rest stop area is limited to the construction, with darkness also maintained in the car park and access road. 

Designed to attract visitors to remote destinations in the country, Norwegian Scenic Routes is a cultural project that unites architects, artists, designers and craftspeople with a common goal of creating destinations across the country through architecture. Along the routes, architectural structures are designed to both integrate and contrast with nature. 

• The Espenes rest stop won an IALD Award of Excellence 2023, and Platinum and Green in the Build Back Better Awards 2023.

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