As in the past few years, CIBSE has reviewed last year’s awards entries to assess building performance across the projects, as well as the quality of the information provided.

In 2021, based on a review of all past entries, CIBSE introduced a data form to accompany the Project of the Year entries, to improve the consistency, quality and coverage of the building performance data provided.

This helps the judging process, and contributes to industry’s understanding of current best practice, in turn feeding into CIBSE activities such as the Net Zero Carbon Buildings Standard (NZCBS).

Since then, entries have been reviewed every year, and updates made to the data forms to reflect evolving practice and improve clarity and data collection.

Quality of data

This year’s analysis confirms that the quality and scope of building performance data continues to increase. The award entries show fewer areas of data uncertainty, more consistent information, and wider coverage of building performance.

While a large proportion of buildings entered into the awards have onsite generation, the energy flows associated with the building and onsite systems are better reported than in previous years. This indicates better metering set-ups, as well as better monitoring and analysis.

SGA Consulting was crowned CIBSE Building Performance Champion for its retrofit of York Guildhall

In recent years, few entries had complete and reliable enough data to estimate the building’s energy use intensity (EUI) with reasonable confidence, but, importantly, this is now possible for the majority of entries.

What the data tell us

Last year’s data shows trends in delivery processes applied across the projects, similar to previous years. As expected, projects often used energy performance modelling (rather than just compliance modelling) – for example, Passive House Planning Package (PHPP) or CIBSE TM54 more generally. Many of them set energy performance targets beyond regulatory compliance, sometimes as contractual targets. They carried out post-occupancy evaluation, with attention to energy use as well as factors beyond it, such as indoor air quality, temperature monitoring, and interviews or surveys of occupants.

The new-build entries had lower energy use than the average building stock, sometimes significantly so; however, energy use was still higher than industry targets from the RIBA 2030 Challenge and LETI for the sectors where these targets are most established, such as homes, offices and schools.

In future years, the NZCBS, due for beta release later this year, will provide a further point of comparison, applicable across a wide range of sectors.

The majority of projects, and all the new-build ones, had onsite photovoltaics (PVs) – in some cases with significant export as well as self-use. The contribution of these PV systems varied significantly across projects, on average around 60-70kWh/m² per yr building footprint (ranging from 35 to 140), covering, on average, around 30% of the building’s annual energy use (ranging from 5% to 55%).

For comparison, in last year’s Technical Update Consultation, the NZCBS proposed an approximate target range of 80-120kWh/m² per yr for non-industrial buildings; this was only a draft and is being reviewed ahead of the beta release.

CIBSE looks forward to your entries, and wishes you all the best of luck!

To enter visit www.cibse.org/bpa

The post Building on performance: CIBSE awards analysis 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.

The project took place over winter 2022-23, and aimed to gather lessons on retrofit and building performance techniques, which have moved on considerably in 10 years.

Its report looks at how robust, meaningful and useful data are collected in an affordable and accessible manner, and is intended to give occupants, designers and decision-makers a good understanding of BPE.

Analysis of the homes aimed to find out what had stood the test of time, and what lessons there were to learn. The team was particularly interested in moisture, insulation options (moisture and combustibility), and the degradation of original solutions (for example, fabric condition and airtightness).

All 10 sample homes were considered best practice or exemplar at the time, and employed a whole-house ‘deep’ retrofit approach. Six were part of the 2009-13 Retrofit for the Future programme.

Six of the properties dated from pre-1919, nine were houses (one a flat), and they were a mix of housing association and privately owned properties.

Their insulation strategies varied, with a mix of external, internal and cavity insulation, and permeable and impermeable materials. Heating, hot water and ventilation systems were also varied.

A two-tiered BPE approach – core and detailed scope – was followed for the project.

The results:

Energy performance
In most of the homes, no major change has been observed in energy performance compared with the original retrofit energy use. The retrofit has delivered long-term benefits, with energy use still significantly lower than in the average stock.

Tellingly, most homes have reported being satisfied or very satisfied with their energy bills. Where space-heating demand could be estimated, it is in line with best practice retrofit standards, significantly below the national average.

The energy use intensity (EUI) is, on average, ~80kWh·m^-2 GIA per yr, which is very favourable compared with UK data (see table, opposite).

Fabric
Fabric efficiency improvements have been shown to be very effective in the long run, with air leakage and heat demand remaining very low compared with the national average. The good level of performance is indicated by the average for the homes of 2.54m³·h^-1.m^-2 @ 50Pa (up from an average of 1.98 ~10 years ago). Airtightness in all homes is still significantly better than pre-retrofit (77% better as pre-retrofits achieved ~11m³/h.m²@50Pa).

The most common weak point reported by the projects was the lesser reliability of external window and door seals after 10 years of use, in particular on large-format elements, such as doors. Airtightness tapes seem to have held overall, as the drop in performance in some houses is minimal. Only a very few instances have been found of material deterioration, and, in most cases, this has been very localised.

Moisture and mould risks were generally low, with good relative humidity (RH) levels in eight out of nine homes measured, and low or very low Build Test Solutions (BTS) Mould Risk score in seven out of nine homes. The study also recorded generally good CO₂ levels in seven out of nine homes.

A focus on ventilation and maintenance emerged as crucial for long-term success. The findings also reiterated the importance of maintenance. Common issues include clearing gutters and downpipes, and windows and door maintenance.

Systems
The report found that complex systems were more likely to fail. MVHR has been shown to be reliable in these case studies. This was not necessarily expected, as these systems were still quite innovative at the time. Ease of controls remains an issue, even in homes where residents report good comfort and relatively simple systems. There are issues with the metering of solar thermal.

Low carbon strategies since Retrofit for the Future have evolved greatly, in parallel with Grid decarbonisation. Eight out of the 10 homes have a gas boiler, and only one a heat pump. The more common approach now would be for an all-electric system (typically, heat pump) and PVs, rather than solar thermal.

Overall, feedback is very positive, with the sample homes showing results significantly better than the Soap Retrofit benchmark. Comfort has been delivered in all houses and winter comfort is rated very highly in the majority of homes; summer comfort is less so, but no worse than the benchmark. Temperature, RH, and CO₂ are within recommended ranges for most homes.

Evaluation techniques
The common methodology was useful to check and agree an approach and bring consistency, with input from all and an Excel sheet for basic energy reporting. The core and detailed BPE methods proved complementary, and the detailed techniques brought useful additional findings. All homes used the same indoor environmental quality sensors. This helped with consistency of data, allowed the use of the BTS platform for many tests, and supported the evaluators for training and queries.

Challenges
There was a small window to monitor homes over winter, after funding was confirmed in January. More preparation time would have been valuable. Despite initial enquiries with the residents and housing associations about their willingness to engage and the availability of energy data, this proved a challenge in a small number of homes once the study began.

More developed templates would have made reviewing and cross-project data collation and reporting quicker and more consistent, and detailed aspects of the methodology could have been modified or made more explicit. 

A researcher’s perspective

Marion Baeli, was co-leader of the project with CIBSE’s head of net zero policy, Julie Godefroy

Many CIBSE members aren’t engaged in domestic retrofit, says project co-leader Marion Baeli, who was partner at Studio PDP until January and is now principal, sustainability transformation, at 10 Design.

She hopes that the information garnered in the study could be useful for the industry in advising retrofit projects. ‘It’s crucial to conduct the right tests at the starting point, employ appropriate methods, understand the caveats, and ensure a good maintenance plan,’ she says.

Baeli advises that there is no ‘one size fits all’ approach to a retrofit: ‘When you’re starting a project, a retrofit coordinator may be useful in creating a detailed plan, or there are training courses, such as the PAS2035 course, that can be valuable.’

She says that some of her clients are clued up and see the risk of being exposed to high carbon assets. ‘Some clients have approached me to help them address the high carbon intensity of their entire portfolio and identify the best strategy for effective decarbonisation.

‘The aim being to assist them in reducing the risk of their assets becoming stranded. Our guidance focuses on decreasing energy demand initially, followed by transitioning to electricity and renewable energy sources,’ says Baeli.

One major change 10 years on is the profusion of heat pumps. ‘We didn’t know then that there was an alternative to gas boilers’ says Baeli. ‘The main issue at the time was to reduce CO₂. Now the target would be to reduce demand sufficiently to enable you to use an air source heat pump.’

The Retrofit Revisit report emphasises the efficacy of retrofit. ‘We want to give people the confidence that it does work and show that it is a good investment,’ says Baeli. ‘Yes, it’s disruptive, but you only have to do it once for the lifetime of the property and, if you take care of it, it will continue to perform.’ 

The post Revisiting retrofits 10 years on: key lessons for the future of retrofit appeared first on CIBSE Journal.

‘A big part of using a gaming engine is enabling user immersion, because interaction and experience are a big part of a digital twin,’ says Miraj Patel, associate graphical information systems (GIS) and digital twin developer at Buro Happold. Another major benefit, according to Patel, is the almost photo-realistic rendering capability that game engines bring to enhance the immersive experience. ‘Depending on how you build it, with a VR [virtual reality] environment users can jump into it and almost feel it,’ he says. 

The innovative use of game engines to enable the creation of immersive digital twins was one of the reasons Buro Happold was crowned Digital Champion at the CIBSE Society of Digital Engineering Awards in December. Game engines enable Buro Happold’s digital twin models of cities, for example, to incorporate vast datasets of geographical and environmental characteristics, to create highly accurate and comprehensive virtual replicas of cities. 

It is the ability to combine information within the digital twins, and use it to run simulations, that reduces decision-making time and enhances collaboration, says Patel. It also enables those using the model, such as urban planners, to make more informed decisions. 

With this enhanced level of detail, municipal bodies are able to use the digital twin to monitor infrastructure performance, or run scenarios to assess the impact of a road closure, say, or flooding. Environmental organisations can assess the impact of developments and their alignment with sustainability goals, while engineering firms can adapt and generate infrastructure designs more effectively.

Levelling up

Buro Happold’s digital twin journey started five years ago, when the team set out to ensure all the data it had and was collecting was saved in a format that was usable universally. To enable all of its various data sources to be used, the engineer put in place a framework and protocols to ensure its data management systems were sound. Patel describes these as ‘technology/software agnostic’ robust data standards.

This data management provides the foundation for Buro Happold to use its data in the development of digital twins for a wide variety of projects, scenarios and applications.

Patel says engineers generally come to the digital team with a problem statement/challenge that needs a digital solution. ‘We call it computational engineering; the idea is that a lot of the work we do can be aided by computation to improve our performance, by enabling us to challenge a problem in a lot more detail,’ he says. ‘The idea is to create a digital replica of a complex environment, a building or a system that allows you to challenge it virtually, to change it easily, and even to break it.’

Some of the areas where computational engineering solutions have been implemented include: masterplanning; facilities/asset management; design review and integration; construction management and progress tracking; scenario simulation; community engagement; building fabric analysis; and automated district energy network design and optimisation

When Buro Happold developed the community heat digital twin for Barcombe (see ‘Heating made to measure’, CIBSE Journal, January 2022), one of the big benefits of having a digital model of the village was that it gave the engineers and the community a comprehensive image of what was happening. For the engineer, it was a way to test various heating scenarios without impacting homes. It also helped enhance community involvement. 

‘We were able to use the digital twin to show “what if” scenarios within a virtual environment,’ says Patel. ‘We could say, “here’s your house, and you can see the predicated energy use and carbon output”.’

Initially, Buro Happold digital twins, such as the one for Barcombe, were developed as 2D and 3D web-based models, using open source QGIS and ArcGIS software to enable geospatial data to be visualised. The digital team works backwards from the outputs the model needs to deliver, and through the engineering steps, to establish the data sets and software required to build the model. ‘You work backwards to define your data requirements, then you have to see where you can source that data to start building up the model,’ Patel explains.

A major constraint with these web-based digital twin models, however, is that they are limited graphically and in the level of interactivity. ‘The web is great when you have a 2D to 3D platform for letting you see 2D and 3D shapes, but it’s not immersive, it’s not interactive, and the renderings are not realistic – so users cannot get the full experience of what they are seeing and what they are building,’ Patel says.

With the digital sector continuing to evolve rapidly, Buro Happold’s digital team talked to Epic Games (the maker of Fortnite) about using its Unreal Engine software to create real-time 3D content for its digital twins. ‘It would allow users to jump into the model and be in a place virtually, which would make it a really useful communication tool for clients and the different engineering disciplines on a project,’ says Patel.

The benefit of using gaming software is that it allows the model to be adapted in real time. ‘We didn’t want to do what everyone else does – preload data into the model, which makes it a huge application. We wanted the data to flow from our database and we had already built the mechanism to enable that,’ says Patel.

‘This gives you a whole new level of useability. It makes the digital model useful, not just for the design or construction stage, but also for asset management, because you can bring in different live data sources by connecting in IoT [internet of things] devices.’ This methodology allows for live-operation digital twins and dashboards to manage a city, for example.

Tomorrow’s epic cities

Epic Games could see the potential in Buro Happold’s proposals and awarded it an Epic MegaGrant. This supported the digital team while it spent time navigating the technical challenges of using a gaming engine to stream geospatial data into an application in real time, then render it and make it interactive. 

‘The MegaGrant allowed us to build up the functionality and to develop new texturing techniques within Unreal to make the buildings look realistic,’ explains Patel. ‘Every time we had a conversation with Epic, we showed them what we were trying to do and what we’d done. They were very interested to push it further; some of the stuff we showed them they had not seen before.’

Buro Happold’s gaming engine-driven digital twin development has progressed to the stage where it is now capable of building advanced interactive digital models for numerous applications. 

‘There are so many possibilities. When a user gets into the VR digital twin, they are able to interact with the data, so they can move buildings around, delete buildings and draw new ones; they can add comments for review and even tag people,’ Patel enthuses. ‘What’s more, everything is coming from a single source of truth: all the data is in one place and all the engineers work from it and update it, so the model is always live and always up to date.’

The London city model data shown on these pages comes from Photorealistic 3D Tiles from Google Maps Platform through Cesium. The level of detail varies based on the source data used to build up the digital twins. BIM, CAD or any other data can be integrated into the digital twin. Buro Happold has created digital twins using the Unreal Engine but currently has non-disclosure agreements with these clients so cannot yet share any images

The generalised methodology Buro Happold has developed allows it to generate digital twins for cities worldwide. Patel uses a masterplanning project to redevelop a city (he is unable to say which one) to explain how these models are being used. 

‘Before the client set about redeveloping the city, they wanted a digital twin of how it exists at this point in time, including assets such as utilities, buildings, trees – even lampposts – so they could overlay the redevelopment masterplan to analyse its impact,’ he says. 

To create the model, Buro Happold takes GIS, planning and budget data for various scenarios, and processes it according to its protocols, to ensure it can be integrated into the Unreal platform and then develop the various functionalities the users need. 

‘A big part of this was being able to take the existing city model and look at where the new buildings would be going, what the scheduling might look like, what roads would be affected, and things like that,’ says Patel. 

‘Using the digital model, you can see what the impact on the surrounding environment might be of closing a road, to help judge what the best option would be, rather than actually closing a road and then having to deal with what happens!’ 

It is not just towns and cities that can be modelled; the Unreal Engine provides the model with enhanced levels of granularity. ‘When you look at a development in a web-based digital twin, you cannot go inside the buildings. Using Unreal enables users to look at the development from outside, with a third-person view, but they could also go inside the buildings,’ Patel says. 

‘In theory, people could walk inside to see what the design would look like, then do a flow analysis to see how people move about, which you could visualise. You could even do a façade analysis to look at the impact of reflections on the space, for example.’ 

Each interactive digital twin is developed as a bespoke model. ‘There are core components, which make it easier to use again and again, but we don’t subscribe to a one size fits all,’ Patel says. 

Development of the digital twin starts with what Patel describes as ‘design thinking’ sessions and user interface (UI) and user experience (UX) workshops, to identify individual user needs and define the model’s functionality. Each user has an account that defines their level of access. ‘We construct personas, story maps and wireframes to design and assess UI/UX, because no-one wants to click through seven pages to get to the information they need,’ he says. 

The generalised methodology Buro Happold has developed means it is not tethered to a single technology, so it can easily develop interfaces and systems that cater to the unique requirements of each project. This adaptability ensures that the digital twin remains scalable and future-proofed, capable of evolving with technology and the data. 

So, what of the future? Patel has just taken delivery of VR glasses and AI-powered smart glasses to help the team develop Buro Happold’s next generation of immersive digital twins.

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3D design, energy compliance or BIM models, created in the design and development stage, exist for the vast majority of buildings. However, these are rarely used to their full potential throughout the building’s remaining life-cycle. We have developed and trademarked the Sleeping Digital Twin initiative – the idea that these dormant models can be ‘awakened’ and turned into performance digital twins – as a means to change this.

By this theory, existing models can be updated, calibrated, and integrated with real operational data to monitor, in real time, how well a building is performing and where there is scope for improvement. It also sheds light on why a building’s energy use might diverge from initial aspirations, enabling engineers to move beyond guesswork, identify any faults, and make informed decisions on the best solutions.

A digital twin can be used to investigate a variety of ‘what if’ scenarios to get a holistic view of the options before money is spent on specific improvement or retrofit measures. Cost, energy and emissions savings, payback periods, and the impact on internal comfort conditions can all be considered, to determine the best route to improving the performance of a building. Furthermore, once the chosen solution is in place, the digital twin can be used to measure its performance against expected outcomes.

Of course, better building performance should mean improved energy efficiency and reduced emissions. As such, turning existing models into digital twins can play a role in accelerating the move to net zero. Lower energy consumption also means lower costs.

While a focus on energy efficiency is crucial, this can’t come at the expense of occupant comfort. The use of a digital twin enables a balance between the two, providing a means to see the impact of different measures on occupants and understand how efficiencies can be realised in a way that’s mindful of their needs. This provides the ability to fine-tune the operation of the building in line with different occupancy scenarios and heating and ventilation requirements.

Using existing energy models in operation can also aid post-occupancy evaluations. By referring back to original design intentions, it’s possible to highlight things that may have been missed, or changed, in the building’s development that could impact how it performs on completion. A digital twin can then be used to identify how to bring a building up to predicted performance levels. In addition, this helps to prevent the same errors from being repeated in the future, ultimately resulting in improved design, build and operation.

Finally, repurposing dormant digital assets into a digital twin can support the attainment of in-use performance certifications, such as Nabers, Breeam and Leed for O+M, by providing the level of data required to illustrate that targets have been met. With these certifications ensuring that optimal performance is obtained, energy, carbon and cost savings can be realised, and the building made more attractive to tenants or buyers.

Our research found that 90% of the 167 architecture, engineering and construction practitioners surveyed see the value of energy models in operation, with the top three benefits of doing so being: to close the performance gap; achieve sustainability goals; and improve operational performance.

The appetite is there for better use of existing models, and digitisation of building performance more broadly, but barriers to making this the norm are still in place. After all, for building services engineers to benefit from the models, they need to be able to access them, and stakeholder collaboration and model handover remain areas that require improvement. 

The physical and virtual should always go hand in hand, but, often, it’s easier said than done to ensure continuity across the complete building life-cycle.

The next steps are not straightforward, but facilitating a shift towards this approach has the potential to ensure building performance is optimised at every stage and that we move closer, and more quickly, towards net zero goals.

About the author
Don McLean is CEO at IES

The post Awakening digital twins appeared first on CIBSE Journal.

When it won the Building Performance Consultancy of the Year (up to 50 employees) at the CIBSE Building Performance Awards 2023, the judges said the consultancy was a good example of a ‘developing practice’, adding that they were impressed by the entrant’s ‘incredible’ focus on net zero carbon and by its demonstration of diversity, inclusion and equality.

‘Our USP has always been a focus on cutting carbon; the clue’s in our name – we’re all about crossing out [X] CO₂,’ says Tom Kordel, a director of the practice and one of its co-founders. ‘While cutting carbon is not new now, 15 years ago it was novel to have a business whose sole focus was to reduce carbon emissions within the built environment,’

From inception, the practice was set up to provide environmental consultancy and MEP design. That is still the case now, Kordel says, although, over time, it has added more strings to the environmental side of the business, such as daylight consultancy and overheating assessments, to provide ‘a more holistic service’. 

Similarly, its MEP services now include energy audits and post-occupancy evaluations, services that Kordel says help its engineers gain an insight into how buildings operate in reality. ‘Without understanding how a building works in operation, engineering designs will never improve,’ he adds.

It is the business’s focus on cutting emissions and on environmental issues that has made it attractive to engineers and consultants with a passion for environmental building design and low carbon engineering. 

Their skills give the practice the ability to look at buildings holistically, which means influencing the architecture to exploit passive design and making designs intuitive to use and operate. ‘If you’re going to focus on driving down energy use and CO₂ emissions, I think the best designed buildings are often the ones with the least amount of building services and that are simplest for people to use,’ says Kordel.

Many of those attracted to work for the practice are women; almost half of its current workforce is female, making XCO2 unusual among engineering consultancies, where, on average, women make up only 14.5% of the staff. ‘We want the background of our team to reflect the society in which we operate, so that balance is important, as is a balance between technical disciplines,’ says Kordel. 

XCO2’s attraction as an employer is no doubt helped by a progressive approach to enabling its employees to achieve a healthy work/life balance. They have the option of working from home three days a week, but, more radically, staff work a nine-day fortnight, with alternate Fridays off. 

Kordel says the policy of working fewer hours was introduced pre-pandemic, initially as a trial to ascertain its impact on business efficiency – but the scheme proved so popular that it has been retained. ‘It gives people the opportunity to do their life admin without having to use their weekend, which has helped a lot in terms of staff retention,’ says Kordel.

Perhaps less unusual in a sector struggling to attract talented engineering students, the business is also culturally diverse, with many of its overseas employees recruited to the business from university Master’s courses. ‘We have always looked to have a diverse workforce in terms of gender and ethnicity, because it brings a lot of ideas and creates a friendly, open, innovative culture within the business – and it does help to win work, because the businesses we work with tend to be culturally very diverse,’ Kordel explains.

The new solar installation at the back-of-house facilities at the Soneva Jani luxury eco resort in the Maldives

Two of the key business sectors in which XCO2 is particularly strong are social housing and luxury resort hotels. On the face of it, these businesses – catering for the opposite ends of the wealth spectrum – would appear to have little in common, but, according to Kordel, both have a vested interest in low energy operation and low CO₂ emissions. 

‘Social housing is very focused on eliminating fuel poverty, so having low energy and efficient buildings is really, really important, while luxury hotel developers and operators tend to keep assets for a long time, so they too have a vested interest in keeping energy use low,’ he explains.

The creation of more affordable housing ‘chimes with what we want to do as a business’, adds Kordel. However, it was the company’s hotel work in Southeast Asia that led to it opening an office in Singapore in 2016. ‘We have a strong reputation with hotel operators in the area, and we felt that being closer to architects and developers based in Hong Kong and Singapore was really important,’ he recalls.

The completed Jazz Yard project for Sixty Bricks, which delivers 83 new homes (50% of which are affordable) and a new NHS health centre in Waltham Forest

Many of the hotels and resorts that XCO2 work on in the region tend to be located on remote islands, without access to an electrical grid or mains water, so its net zero design is a practical necessity rather than a nice-to-have solution. ‘To have a holistically sustainable development, circularity around water, waste and energy is important, as is solar energy generation,’ Kordel explains.

XCO2 is also involved in charitable work in the region, including with the Hemis Monastic School in Northern India. Here, it is working pro bono on the design of a new school for Buddhist monks, located next to a 17th-century Buddhist monastery. The scheme is designed to use predominantly passive means to achieve thermal comfort in a cold, high-altitude desert with annual temperature swings of 60^oC.

Site photo from Hemis Monastic School, a new residential school for 500 trainee monks in Northern Ladakh , 13,000ft up in the Himalayas

Key to the success of the school’s challenging design is dynamic thermal modelling. This has been used from the earliest design stages to test and fine-tune a variety of measures – such as Trombe walls – to improve the building’s performance. Computational fluid dynamics have also been used to design and size the building’s solar latrines, which feature dark-painted solar chimneys to passively ventilate the toilets.

The use of digital tools and digital innovation are seen as potential growth areas for the business – an opportunity that has led to the company setting up the XCO2 Lab, to help it identify problems and time-intensive processes ripe for automation. The lab is intended to encourage interdisciplinary collaboration and is led by Aidan Kelly, technical lead for the CIBSE Society of Digital Engineering steering group and contributor to CIBSE Journal.

The Soneva Jani luxury eco resort in the Maldives

In addition to contributing articles for publication, XCO2 shares knowledge by making time for its engineers to get involved with industry initiatives such as LETI and, more recently, the UK Net Zero Carbon Buildings Standard. So what’s next for the developing practice? 

‘Now that we’re post-pandemic, we want to push towards growing the business, our client base, and the scale of projects we work on,’ says Kordel. 

‘Alongside the interesting, much smaller, more bespoke projects that we enjoy doing, we’re now working on schemes with thousands of homes where we can have an even bigger impact.’

The post The X Factor: XCO2’s holistic approach to environmental consultancy appeared first on CIBSE Journal.

Speakers and exhibitors focused on key topics, including the impact of the Building Safety Act, embodied energy, heat pumps and digital tools. There was time for celebration, too, with the CIBSE Building Simulation Awards and Society of Digital Engineering Awards held during the event.

Among the seven stages at London ExCeL was, for the first time, Light2Perform, and content around building safety was provided by CABE’s Built Environment Live, which ran alongside the main event. 

Build2Perform Live was opened by CIBSE vice-president David Cooper FCIBSE, who told delegates that it had attracted a record number of registrants. He was followed by a keynote from the team developing the Net Zero Carbon Buildings Standard (NZCBS), which includes Julie Godefroy, head of net zero policy at CIBSE, and Katie-Clemence Jackson, sustainability associate at QODA and chair of the NZCBS technical steering group. 

The group aims to achieve a robust definition for net zero buildings in the UK and create a rule book to assess new and existing buildings. A new tool is also being developed to balance ‘top-down’ budgets and ‘bottom-up’ performance levels to produce net zero carbon pathways and limits.

‘We have modelled different scenarios of decarbonisation to help set new limits and requirements in the standard, treating operational energy and embodied carbon as one entity’, said Clemence-Jackson. Godefroy spoke about future updates. ‘We need to look at district heating and cooling networks, and how we assess these and set limits,’ she said.

Andrew Moore, from the Health and Safety Executive, led a talk on the Building Safety Act. He explained that there are significant new requirements to demonstrate competence on all regulated building work, not just on ‘higher-risk buildings’. ‘Competence cuts across the whole of the industry. It’s a key driver to improving the built environment, to reach all of our strategic aims, not just building safety,’ he said.

‘We want to see how you ensure that your work is in compliance with the Building Regs; industry needs to step up and take responsibility for its designs.’

TM65’s growing influence

CIBSE’s TM65 series has helped engineers understand and calculate embodied energy in designs and systems. A further four TM65 documents are set to be published around calculating embodied energy, including local addenda for the USA and the UAE. 

Francisco Sierra, senior lecturer at UWE Bristol, highlighted the lack of data in the UAE on embodied carbon. He said the TM65 aligns with local decarbonisation policies.

Amazon’s senior programme manager for sustainable buildings, Phil Birch, outlined how the company has used TM65 to align with its Climate Pledge. ‘We’re doing countless calculations to work out the embodied carbon of our primary buildings, as well as the MEP we use. It’s about data-driven decision-making; without data you’re just another person with an opinion,’ he said. 

Amazon is working with Introba to create TM65.3, which will cover embodied carbon in logistics buildings to improve the accuracy of calculating the carbon footprint of these spaces. Other future versions, such as TM65.4 will cover embodied carbon in office HVAC systems, are in progress. 

Kristina Allison MSLL MCIBSE, vice-president of the SLL discussed ‘practical journeys throughTM66 (which she co-authored) and TM65.2’, a circular guide and tool that helps asess lighting embodied energy.

Kristina Allison MSLL MCIBSE, vicepresident of the SLL

Making cities resilient

Reducing emissions from the cities will be fundamental if issues around global climate change are to be solved. This was the message from physical geographer Gerald Mills, who highlighted that 70% of the world’s CO₂ emissions are from cities.

Mills, associate professor at University College Dublin, stressed that a combination of adaptation and mitigation was required to ensure the world’s cities could cope with the impacts of current and future hazards. He cited the example of the French city of Nîmes, which has implemented measures to create accessible outdoor cool spaces. Heat gain has been reduced by maximising shade via tree canopies, increasing the amount of water cover, and enhancing ventilation.

Other speakers included Darren Woolf, head of building physics for Wirth Research and visiting professor at Loughborough University, who explained the role of the UK Urban Environmental Quality Partnership. Hosted by CIBSE, members are working on publications covering topics such as urban vegetation systems, outdoor thermal comfort, city wind microclimate guidelines, and modelling of outdoor air quality.

The challenge of tackling overheating in the UK’s housing stock was examined by Passivhaus designer Joseba Perez de Larraya Sola, of Pollard Thomas Edwards, and Kai Salman-Lord, senior engineer at Max Fordham. They looked at how greater use of shading devices for buildings could help tackle this problem, especially in a residential setting. The pair have been heavily involved in the launch of a new guide from the Good Homes Alliance, Shading for housing, which seeks to embed shading as central to a building’s design and built in from the start.

Staying cyber secure 

An important issue that is often overlooked in the industry is cybersecurity. Sweco digital manager Andrew Krebs shed light on the pervasive impact that breaches  of digital security can have, saying ‘it affects everything we are doing, from safety to decarbonisation’.

Carl Collins, head of digital engineering at CIBSE, highlighted the existing gaps in securing energy systems, pointing out a lack of understanding of how building elements interact: ‘We need to really understand the connectivity of what we are installing, and the information to which it has access.’

He urged the audience to seriously consider security, and drew parallels with the comprehensive approach taken towards other potential threats, such as fire. 

CIBSE’s technical officer Hywel Davies HonFCIBSE expressed concern over the apparent lack of interest in cybersecurity. ‘It is often referred to as the monster in the room, but it only becomes scary when you don’t think about it. Understand where threats may come from and address it,’ he said.

A session introduced by Julie Godefroy gave an overview of the Retrofit Revisit project, supported by Historic England and CIBSE and co-led by Studio PDP and CIBSE. The project applied building performance evaluation techniques to 10 homes that had been subject to a deep retrofit over the past 10 years. It particularly looked at energy performance and indoor air quality, and found that the retrofitted homes still performed extremely well in terms of energy use. ‘Energy performance has not significantly degraded at all, which is a very positive finding. It’s much better than the national average, and many of the homes perform more or less in line with Leti targets,’ Godefroy said. 

Air leakage was slightly higher, with degradation of doors and windows being the key contributor. Feedback from residents was that conditions were comfortable, but summer comfort rated less well than winter comfort. There were some issues around system maintenance, said Godefroy, with complex services generating more problems.

The risk of mould from ambient conditions, was assessed by measuring relative humidity and surface temperature, and tests looked at the movement of moisture through the fabric. Mould related to ambient conditions was rated as very low risk across seven of nine homes tested and there was generally low CO₂ across all homes, indicating good ventilation. 

Pumped for growth

Independent consultant Roger Hitchin shared research by the IEA Heat Pump Technologies programme on non-domestic heat pump retrofits. The Annex 60 programme (Heatpumpingtechnologies.org/annex60) is an international collaboration aimed at identifying and quantifying technical options for non-domestic retrofits, and providing advice and tools to help decision-makers. 

‘There is very little guidance for building owners and tenants,’ said Hitchin. ‘We want to provide high-level guidance so they can look at different heat pump systems.’

The event attracted leading building services brands from across the industry

The project will link to case studies and Hitchin is particularly keen to include studies showing comparative costs. An online tool will invite users to describe the building and its HVAC systems and the degree to which fabric will be upgraded. It will then come up with a shortlist of solutions worth investigating.  

Ken Gordon, CEO of the Ground Source Heat Pump Association(GSHPA) , spoke of the upcoming revised TM51 guidance on GSHPs, which would include information on shared ground loop systems. These are increasingly popular because they offer economies of scale, said Gordon.

Accessible acoustics

In a discussion about wellbeing in the built environment, Foster & Partners associate partner Milena Stojkovic FCIBSE said: ‘We have a responsibility to create environments that are healthy and inclusive to use.’

There has been a shift away from traditional accessibility measures focused on physical impairment to a more inclusive approach for neurological conditions, said Rob Turpin, head of sector healthcare at the BSI. Challenges have been identified relating to lighting, acoustics, route preview, signage, and clarity in buildings.

Turpin introduced PAS 6463 Design for the mind, a world-first standard that covers designing for neurodiversity. He hopes it will be a catalyst for international standardisation.

Tin Oberman, senior eesearch fellow at UCL, discussed the importance of soundscapes and inclusive acoustics. He and Turpin highlighted that the majority of auditory research acoustics have been driven by healthy-hearing participants, and knowledge about how most people perceive sound is missing. 

Speakers noted that the event did not create the most accessible acoustic environment. Rachel Smalley, head of inclusive design at Jacobs, said future approaches must ensure the environment is suitable for a diverse population, and that requirements are integrated from the outset.

Tim Galloway, deputy director, building safety programme, HSE

Crossing generations 

A Young Engineers Network (YEN) panel focused on how to foster collaboration between older and younger members, including ‘buddy’ systems and mentoring. 

Ruth Tatanga MCIBSE, chair of YEN London emphasised the importance of examining what seniors can learn from younger colleagues, and Jack Kenny, senior M&E consultant at RLB, agreed. 

‘Play to the strengths of both generations, foster flexibility, and provide opportunities without rigidity,’ he said.

• For more information on Build2Perform Live, visit bit.ly/CJLIVE23

The post Platform for change: insights from CIBSE Build2Perform Live 2023 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.

Project of the Year was divided into six awards, and showcased a diverse range of entries. There was an emerging theme of prioritising wellness within buildings, plus a heightened awareness of climate change impacts. Judges observed a commendable understanding of the challenges faced by the sector, saying that projects are ‘extending their focus beyond just the energy performance, to a space where building performance becomes far more holistic’. In particular, Project of the Year – Retrofit drew attention for its emphasis on embodied carbon conservation, highlighting the crucial need to retrofit older buildings to meet net zero targets. 

The judges were impressed by how these standout projects exemplified effective solutions, showcasing a positive shift towards sustainable building practices. Similarly, in the Project of the Year – Commercial and Offices, the judges saw an impressive amount of innovation and creative thinking.

A new category, Project of the Year – Leisure, was introduced, acknowledging a number of exceptional projects that delivered on their buildings for leisure through a spectrum of servicing methods – from passive to highly complex and efficient systems – with the building’s purpose being a priority. 

Ravelin Sports Centre – Max Fordham, Project of the Year - Leisure

The Best Digital Innovation Award, introduced last year, proved highly competitive, with more than 20 entries of ‘exceptional quality’. Judges noted a prevalent theme of decarbonisation and a significant shift towards incorporating machine learning into real-world applications. 

The inclusion of robust data across various categories, including Best Digital Innovation, was praised, emphasising the importance of tangible performance metrics as a key way of visualising performance. However, judges for the Project of the Year – Residential category expressed a desire for more data-centric schemes, signalling a potential focus area for future innovations in the industry.

Facilities Management (FM) emerged as a standout category this year, with a robust field of entries. The judges commended the ‘positive impact FM can have when it takes an active role in engaging with building users, especially in the context of decarbonisation and energy management’. Collaboration and knowledge sharing across the entire value chain were highlighted as promising trends.

The Building Performance Consultancy award was divided into categories based on employee count, to recognise outstanding practices that excel in collaboration, innovative protocols, and inclusivity.

In the category for firms with up to 50 employees, the judges saw some ‘stunning entries’ from consultancies engaging in best practice, knowledge sharing and wellbeing. ‘We’re seeing companies that are really focusing on the humans who actually work for them – it’s great,’ the judges remarked.  

The 51-300 employees category highlighted the importance of inclusivity, but called for more innovation. The 300+ employee category demonstrated significant improvements from the previous year, showcasing a clear commitment to addressing the climate challenge through extensive knowledge-sharing initiatives and upskilling programmes. Training and development of young staff was key for many of the firms shortlisted.

York Guildhall – SGA consulting, Project of the Year - Public Use

The CIBSE President’s theme of engineering leadership was evident in the Engineer of the Year category. Judges noted a clear ability among contenders to embrace knowledge sharing and a genuine willingness to develop others. They were also pleased to note the diversity of candidates from across building services, with the pandemic cited as improving our ability to communicate with anyone, wherever they may be in the world. 

Similarly, the Learning and Development category showcased strong entries that focused on the dissemination of knowledge throughout the industry, with an emphasis on areas that have the most impact on building performance. Peer-to-peer learning was highlighted as an important mechanism for transferring specialist knowledge to others.

The Collaboration Award demonstrated the industry’s recognition of the critical role collaboration plays in achieving optimal outcomes, with a noticeable trend towards using data analytics for enhanced decision-making. The entries demonstrated the ‘art of the possible, and where we all need to get to’, said the judges. 

Hackbridge Primary School – Introba/Architype, Project of the Year - Leisure

Embodied carbon was another key theme throughout the categories. The Embodied Carbon Award highlighted the industry’s commitment to reducing embodied and operational carbon, with a growing awareness of end-of-life emissions. The judges were impressed by the sector’s dedication to practicing circular economy principles.

A commitment to meeting net zero goals was showcased in entries for Product or Innovation of the Year, which was divided into air quality, thermal comfort and wellbeing categories.  A wide range of products was seen in the air quality section, including for refrigeration, water heating and ventilation. Entries showed an understanding of the need for flexibility of application, as well as maintaining regulatory standards. ‘The range of innovations demonstrates that the innovation doesn’t need to be epic to be influential and beneficial,’ the judges said. 

Ross Lucas Medical Sciences Building, University of Lincoln – BAM Design & Yonder, Project of the Year - Leisure

The winners will be announced at the awards ceremony at Park Plaza Westminster Bridge, London, on 29 February 2024. To book a table, visit www.cibse.org/bpa 

The post Setting the standard: 2024 CIBSE Building Performance Awards shortlist appeared first on CIBSE Journal.

To understand the scheme’s operational performance, landowner London Legacy Development Corporation (LLDC) commissioned an independent post-occupancy evaluation (POE) pilot on the first of four phases of Chobham Manor. Buro Happold was engaged to head the multidisciplinary team for the Phase 1 POE, working with Hawkins\Brown and SOAP Retrofit. Monitoring took place over a 14-month period from October 2020 to November 2021.

Chobham Manor was delivered through a development agreement led by Chobham Manor LLP (CM-LLP), involving Taylor Wimpey, L&Q housing association, and LLDC. The design team comprised five architects and a landscape architect, with PRP as lead masterplan architect.

Design intent
The housing was designed to be child friendly, sustainable and inclusive, with inspiring landscapes and public realm. Central themes were ‘designing for families’, ‘building a community’, and ‘everyone lives by the green’. During the design stages, the scheme was reviewed against these objectives and wider environmental performance targets. All dwellings were required to achieve ³75 credits (exceeding Level 4) in the Code for Sustainable Homes, with fabric energy efficiency standards meeting Level 5 and 6 requirements. Airtightness targets were 5 m³·h^-1·m^-2 @ 50Pa for houses and 4 m³·h^-1·m^-2 @ 50Pa for apartments and maisonettes. The development was required to reduce regulated CO₂ emissions by 40% compared with Part L 2010. Across the four phases, 25 ‘exemplar homes’ targeted zero regulated emissions through on-plot measures only.

All dwellings have smart meters (including water meters) and are connected to the Stratford district energy network, which provides district heating from gas combined heat and power, with a feed of biomass heat.

Post-occupancy evaluation
The Phase 1 POE included a resident survey, focus groups, homes interviews, walkabouts with residents, energy and water monitoring, indoor environmental quality measurements, controls assessments, thermal imaging, an urban greening factor evaluation, and a ‘lessons learned’ workshop.

Energy use
Anonymised district heating and hot water data for all 259 homes was provided by the energy provider for 26 months from September 2019. For 35 homes that consented to the POE, this data was analysed in more depth at a property level. Monthly electricity readings were provided by residents for 14 months from October 2020, covering 29 households (11% sample).

Site-wide measured space heating was 25kWh·m^-2 per year, compared with 50kWh·m^-2 per year for the average new-build home. Domestic hot water and electricity usage was low compared with the new-build average, at 30kWh·m^-2 per year and 32kWh·m^-2 per year respectively. For electricity, in 13 properties with half-hourly electricity sensors fitted, peak household demand was 8.1kW (although this home had an electric vehicle). For the remaining properties, peak was 1.7kW to 3.5kW.

On average, properties used 51-64% more energy for heating and hot water per year than SAP predicted. For the 10 properties where living room and main bedroom temperatures were monitored, winter temperatures were 10% higher on average than SAP modelling assumes (19°C). Average airtightness (from as-built Energy Performance Certificates for Phase 1 dwellings) was 4.2m³·h^-1·m^-2 @ 50Pa for houses and 3.2m³·h^-1·m^-2 @ 50Pa for apartments and maisonettes.

 Occupant satisfaction
Respondents expressed high overall appreciation of the neighbourhood (87% positive ratings), block/street (82%) and homes (79%), and 64% of the 100 respondents plan to stay for five or more years.  In terms of design, respondents were particularly satisfied with daylight (89%) and temperature in winter (80%). Artificial light (79%) and general ventilation (74%) also performed well. Noise from neighbours achieved 62% satisfaction (+12% neutral responses) and noise from outside achieved 50% satisfaction (+16% neutral responses). In summer, overheating was a dominant concern in the quantitative survey results for Phase 1 (only 33% satisfaction). Focus groups revealed concerns over district heat network costs and the quality of landscape maintenance.

 Thermal comfort

To investigate the overheating observed in the resident survey, temperature sensors were installed in 11 homes. Across all properties monitored, the average temperature in bedrooms went above 26ºC for 2.6% of the year compared with the design target of 1%.

Phase 1 was designed to be compliant with CIBSE Guide A (2006) criteria for overheating assessed under the UKCP09 future weather data, based on a medium-emission scenario, moderate percentile (50%), for a 2030 predicted London climate. This design criteria has since been updated with CIBSE TM59 (Phase 3 onwards). A contributing factor to the overheating observed in Phase 1 may be that the thermal comfort strategy included measures reliant on occupant control (use of blackout blinds, operation of windows, and so on), allowing some of the physical design criteria – for example, a g-value of 0.735 was selected for windows compared with solar control glass at 0.37-0.49 – while still achieving compliance. The decision to relax the glazing g-value was also noted as an intervention to support compliance with fabric energy efficiency criteria.

Urban greening factor and water use

The POE included an urban greening factor assessment by The Green Infrastructure Consultancy and Hawkins\Brown. Chobham Manor was designed before the introduction of the Urban Greening Factor (UGF) calculation within the new London Plan. However, the site performs well, with a UGF score of 0.308, calculated as part of the POE (against the new London Plan requirement of 0.4).

The Phase 1 POE showed average normalised water consumption across all units at 126 litres per person per day, compared with the design target of 105. The UK national average is 142 per person per day. Within Phase 1, 10 homes had rainwater harvesting, but were not subject to the POE.

The POE scope also included holding ‘lessons learned’ workshops, with the project delivery team reflecting on what worked well and what could have been improved. Timely resolution of snags, integration of social housing and the resident handover process were noted as areas of critical importance.

Summary
This is one of the first residential POE studies released since the Greater London Authority’s (GLA’s) ‘Be Seen’ London Plan came into force. This policy explains how developers and owners should monitor major developments and report operational energy performance. The scope of the POE also covers studies beyond current policy, particularly in terms of social and functional evaluation.

The POE showed that perceived barriers with data protection can be overcome with a thorough, transparent process. Studies were conducted in line with General Data Protection Regulations, supported by a Data Protection Impact Assessment, privacy notice, consent form, ‘do and don’t’ guides, and a data-sharing agreement.

An ‘issues and mitigations’ table has also been prepared for CM-LLP and LLDC to work through actions identified. Learnings from the POE have been shared by LLDC with residents and industry to inform the development of future POE approaches. LLDC is in the process of rolling out POE across the completed Olympic site.

The pilot POE methodology can be shared with other client bodies. We hope the findings build confidence in the value of POE and accelerate its uptake, as it is a vital mechanism for ensuring neighbourhoods thrive and resident views.

Mark Dowson CEng FCIBSE is an associate director in the Buro Happold sustainability team

References: The Phase 1 POE report is publicly available here. 

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