Secondary legislation regulations and guidelines are being used as the working values against which indoor air quality (IAQ) can be assessed.

It can be regulated via health and safety regulations, such as the Control of Substances Hazardous to Health (COSHH) Regulations (2002), to which all places of work have to adhere. Regulation 6(1) of COSHH states that an employer ‘should carry out a suitable and sufficient assessment of the risks to the health of your employees and any other person who may be affected by your work, if they are exposed to substances hazardous to health’. Regulation 10 of COSHH specifies that monitoring is required ‘when measurement is needed to ensure a workplace exposure limit (WEL) or any self-imposed working standard is not exceeded’.

There are legally binding WEL for around 500 substances, listed in HSE EH40/2005. However, WEL only relate to personal (exposure) monitoring of people at work, are calibrated for a healthy working-age adult, and can’t be readily adapted to evaluate or control prolonged, continuous or non-occupational exposure. So, for most office and education settings – and all public and residential buildings – WEL cannot be used to assess building occupant exposure to IAQ.

New buildings, however, are covered by the recently updated Statutory Instrument Building Regulations (2010). Now included in Approved Document F1 is ‘Means of Ventilation’, providing statutory guidance on ventilation requirements to maintain IAQ.

Within Approved Document F1, Appendix B: Performance-based ventilation, average indoor air pollutant guideline values are set for carbon monoxide (CO), nitrogen dioxide (NO₂), formaldehyde, total volatile organic compounds (TVOC) and ozone (O₃), largely based on World Health Organization (WHO) guidelines. However, as the document relates to building performance guidance, these values are performance criteria of the assessment of ventilation, not occupant exposure assessment criteria.

For several years, regulations, standards and guidance on IAQ for school buildings have been set out in the UK government’s Education and Skills Funding Agency Building Bulletin BB101. This includes guidelines on ventilation, such as setting a maximum CO₂ in teaching spaces, and specific guidelines on IAQ, mainly based on WHO guidelines that ‘should be used for schools’.

The WHO first published air quality guidelines in 1987, which have been updated since. They ‘serve as a global target for national, regional and city governments to work towards improving their citizens’ health by reducing air pollution’.

In 2010, the WHO published guidance on risks associated with pollutants commonly found in indoor air (benzene, CO, formaldehyde, naphthalene, NO₂, polycyclic aromatic hydrocarbons, radon, trichloroethylene and tetrachloroethylene), and updated their (general) air quality guidelines in 2021 (see Table 1).

It should be noted that WHO general air quality guideline values ‘do not differentiate between indoor and outdoor exposure’, so they are applicable indoors. Some of the latest 2021 guidelines supersede its specific 2010 IAQ guidelines (eg, for CO and NO₂).

They are relevant in all countries and in all exposure settings where COSHH WEL are not appropriate. Organisations, including CIBSE, point to these guidelines for IAQ monitoring. In recent years, other organisations have published IAQ guidance.

About the author
Oliver Puddle is technical director at DustScanAQ

The post The good, bad and illegal: rules and guidelines for IAQ appeared first on CIBSE Journal.

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.

New lighting standards are moving away from task-based design towards a more space-orientated approach, but project decisions are still often dictated by capital cost, energy efficiency and carbon reduction, rather than by the welfare and productivity of people.

Calculations by the World Green Building Council a decade ago found that, on average, a typical business spends 9% of its revenue on rent, 90% on salaries and benefits, and only 1% on energy. However, I regularly see businesses with the sole focus of reducing that 1%, which can inadvertently impact the wellbeing of staff.

This has been driven in part, perhaps, by guidelines and industry priorities post-Covid, which have shifted the focus from health and wellbeing to reducing carbon.

New legislation

For existing buildings, this decision-making process has been exaggerated recently by changes in legislation, which will force thousands of businesses, schools and universities to source alternative lighting. The quality and effectiveness of that new lighting, however – and its ability to embrace comfort, safety and productivity – will be determined by the questions asked upfront by the people specifying and designing the lighting system.

I regularly speak to businesses about how best to make this transition. Some organisations have grasped it as an opportunity to not only switch to LEDs, but also to consider a range of long-term benefits from their new lighting, such as controls to deliver low-energy solutions.

Others have taken a more conservative approach by choosing lighting solutions that satisfy the lower end of the compliance spectrum and seeking only to reduce that 1% of revenue dedicated to energy. This short-term approach has the potential to cause issues later.

Making people part of change

I recall a conversation with a facilities manager at a large local authority, who felt that current guidance wasn’t fit for purpose and was responsible for the negative response to a recent office refit. Fluorescent lighting was upgraded to LED, resulting in staff complaining of excessive brightness and flicker, which caused headaches, loss of concentration, and even absenteeism.

The lighting refit had been guided by just two principals: improving energy efficiency and achieving 500Lux. No thought had been given to factors such as glare, colour temperature or the regulation of lighting levels via the use of controls. Crucially, no effort was made to tell employees in advance about the change, its rationale, and what to expect. 

End-user engagement is important to achieve buy-in, because people are often instinctively averse to change, and without adequate information they are more likely to push back.

Whitecroft regularly suggests producing information cards for workstations before a refit, to explain what is going to happen, why, and what to expect. For example, the lighting may feel different and may be cooler, but it is in line with best practice.

Take control of change

Another option open to clients is to make gradual changes using lighting controls, to give people time to adjust. While this used to be complex, there are now freely available apps and control systems, such as Whitecroft’s Organic Response, that allow the owner to take much greater control of adaptations.

By managing the change in this way, the owner can fine-tune the solution for users’ comfort while also helping to satisfy carbon targets, energy costs and the bottom line. These factors are important and should be used to drive change and innovation, but not to the detriment of people.

The savings an organisation can achieve by reducing its 1% energy cost should be an important part of a business case for change, but must always be balanced with wider considerations, such as the long-term welfare of employees – which is where 90% of costs are incurred.

A great example of this in action is the Cundall office, One Carter Lane, London, which became Europe’s first Well-certified office. This people-centric approach has contributed to a 27% drop in staff turnover and 50% lower absenteeism. Like many of the best buildings, One Carter Lane demonstrates lighting that is resilient and adaptable to the shifting priorities of today, so that it can continue to be fit for purpose for tomorrow.

About the author
Tim Bowes is head of academy for Whitecroft Lighting, light concept adviser for the Well Standard, and chair of the Education and Membership Committee for the Society of Light and Lighting.

The post Putting people first: lighting for wellbeing appeared first on CIBSE Journal.

For the first time, the event will incorporate Light2Perform, with an extensive programme curated by the Society of Light and Lighting (SLL) and the Lighting Industry Association. Also co-locating with Build2Perform Live is the Chartered Association of Building Engineers’ (CABE’s) Built Environment LIVE, which has themes of performance, compliance and safety.

A CIBSE-accredited CPD programme will run alongside Build2Perform. Curated by CIBSE Divisions and Special Interest Groups, and the Build2Perform Live advisory committee, it will feature invited specialist speakers from across the built environment.

Build2Perform’s key themes this year are heating for net zero, climate adaptation, electrical services, smart technology, building safety, and health and wellbeing. 

Net zero, safety and overheating

The keynote session on day one will discuss how the UK Net Zero Carbon Buildings Standard will impact environmental design. This will be followed by an session on virtual, augmented and virtual realities, which will delve into artificial intelligence and discuss the benefits and pitfalls of handing building control to the machines. 

Representatives of the government and the Building Safety Regulator (BSR) will explain how the Building Safety Act is revolutionising the way buildings are procured, designed and maintained. Building safety is also the theme of a session organised by the Society of Façade Engineering. 

Thermal comfort is key to health and wellbeing, and Build2Perform will feature a session on the latest research and industry developments in assessing overheating in buildings. Speakers include Kevin Lomas, Susie Diamond and Becci Taylor. 

On day two, the keynote will cover CIBSE’s TM65: Embodied energy in building services, and look at TM65 guides specifically for Middle Eastern and North American regions. 

Winners of the annual Society of Digital Engineering Awards will also be announced at Build2Perform. 

The CIBSE Resilient Cities Group is hosting a seminar on advances in urban digital planning and modelling for climate-resilient and healthy cities, and other sessions will look at indoor air quality and guidance on avoiding mould and damp. 

In the CPD theatre, the CIBSE Lifts Group, with Adam Scott, will present on the whole life carbon of lifts, while Nick Mellor, of the Lift and Escalator Industry Association, will discuss building safety and the evacuation and use of lifts by firefighters.

Light2Perform

Key themes of Light2Perform include emergency lighting, external lighting, dark skies light pollution, decarbonisation, health and wellbeing, regulation, and sustainability. 

The conference will feature the launch of LG7 Lighting for offices and LG14 Control of electric lighting, and the Young Lighter of the Year competition will be announced.

Light2Perform’s technical programme will cover ever-tighter eco-design requirements and the challenge of reducing embodied carbon, and has been organised by leading lighters Bob Bohannon, Sophie Parry and current SLL president Helen Loomes.

The BSR’s deputy chief inspector of buildings, Chris Griffin-McTiernan, will give a keynote at Build2Perform Live, and there will be sessions on fire safety, new-build housing quality, building retrofits, and zero carbon building performance.

The event is a fantastic opportunity to network and be on top of all the huge changes happening in building services as we strive for net zero and building safety. The Journal hopes to see you there.

Featured Exhibitors:

The post Get ready for CIBSE Build2Perform Live 2023 appeared first on CIBSE Journal.

The Department of Health and Social Care (DHSC) set up a team to develop up-to-date guidance for landlords, working with a multidisciplinary expert group and advice from the Committee on the Medical Effects of Air Pollutants. The resulting guidance was published on 7 September.

The guidance sets out the responsibilities of landlords, in both the social and private sectors, for ensuring that their accommodation is fit to live in and free from serious hazards, including damp and mould. It makes very clear that they must act with urgency to deal with damp and mould in their dwellings, and must protect their tenants’ health.

It includes guidance on the requirements of the Building Regulations that relate to minimising the risk of damp and mould, and that they apply whenever building work is carried out in the dwelling. The coroner in the Awaab Ishak case found that his family’s flat was not compliant with Building Regulations.

The guidance is very clear that tenants should not be blamed for damp and mould in their home, and that they are absolutely not the result of so-called ‘lifestyle choices’. Washing, showering and doing your laundry are not ‘lifestyle choices’, and any dwelling must be adequately heated and ventilated to prevent them causing damp problems.

Where moisture problems are reported, landlords are required to act quickly to determine the underlying causes, whether they are down to inadequate ventilation or structural faults in the building.

In addition to the new guidance on avoiding damp and mould, the government released further guidance on the Housing Health and Safety Rating System, used to assess the safety of homes and identify and prioritise health and safety risks.

Forthcoming legislation in the Renters (Reform) Bill and the new Social Housing (Regulation) Act 2023, are intended to improve housing standards by:

• Creating a statutory duty on social housing providers to appoint a senior health and safety lead; significant statutory duties to monitor compliance with health and safety provisions and raise compliance risks or failings with senior management (see Section 10 of the 2023 Act)
• Introducing new requirements for landlords to address hazards such as damp and mould in social homes
• Empowering the Housing Ombudsman and changing the law to enable social housing residents to complain directly to the ombudsman
• Reviewing the Decent Homes Standard and applying it to private rented homes for the first time
• Introducing new professional standards and requiring senior housing staff to hold, or work towards, recognised housing management qualifications
• Introducing an ombudsman for private tenants.

Landlords and their health and safety leads need to read this guidance and adopt the best practices it sets out. Those who work in social housing or manage private rented homes would be well advised to read section 10 of the Social Housing Act as well.

In addition to protecting tenants’ health, it will help to prevent a repeat of the utterly avoidable tragedy that befell Awaab Ishak’s family.

The post After Awaab: guidance on protecting tenants’ health appeared first on CIBSE Journal.

At the ASHRAE Conference in June, he reported on how models that assume ‘well-mixed’ room air can significantly underestimate levels of room-sourced contaminants at specific locations in the space. He demonstrated that spatial distributions of potentially harmful contaminants, are strongly influenced by ventilation supply and extract locations, geometries, and flowrates.

In his presentation based on his paper Use of an air tracer to investigate air mixing: the truth behind the myth, Smith explained that air quality in occupied buildings was determined by a complex integration of flows of contaminants that might include pathogens and particulate matter from outside, including wildfire smoke. 

Activities such as food preparation, off-gassing from finishes, and allergens from flora and fauna add to the cocktail.

Smith noted that concern over a particular contaminant is related to the rate of generation; how much is in a particular space; and how long it remains. This is often referred to as the hazard emission scenario.

This might be explored using the dilution equation: Effective air change rate (ACR’) = Effective volume flow (Q’) / Room volume (V) where Q’ = Q / K with Q being the actual ventilation flowrate and K the ‘mixing factor’ for a space and system.

The mixing factor K makes an allowance for incomplete mixing of the air and is likely to be between 2 and 5, depending on conditions and ventilation system. Lower values of K correspond to good ventilation mixing conditions with a value of 1, indicating contaminants are dispersed uniformly in the space. Under a well-mixed scenario, with a contaminant released in the space, Smith said the ACR is simply Q/V that provides a reduction in concentration with an increase in airflow. 

The assumption is that the contaminant disperses into the space until it reaches a homogeneous concentration and then, once the generation stops, it begins to decay. However, the mixing factor does not account for dispersion or spatial variation in concentrations in the space and the decay that occurs after generation stops.

To compare theoretical with actual movement of air, Smith’s team built a hybrid model for the University of California that uses a general dilution equation and other established modelling techniques, including those from the University of California and the US Environmental Protection Agency. The model (available at https://smartlabs.i2sl.org) has input parameters including space dimensions, airflows, and the hazard emission scenario in terms of the contaminant of concern – the model dataset includes 500 possible contaminants. 

The outputs provide the individual dose, accumulation and decay at different air change rates and the accumulated ‘dose’ area under the curve. 

To test how well this model performed compared to the real world, Smith’s team undertook tracer gas tests to test for a ‘well-mixed’ scenario, how uniformly the contaminants disperse and decay and evaluate the results.

For the initial tests, they employed a 7.62m x 8.8m x 3.05m high test room and added contaminant at the centre, see Figure 2. 

In the first test (Case 1), there were two 360-degree supply ‘mixing’ diffusers and two exhaust points at low level. A separate fan was added to mix the air. Using a methodology of 10 minutes of background ventilation, followed by 10 minutes of contaminant generation and 40 minutes of decay, they measured the tracer gas levels across the space and compared it with the model. Sampling points 1 to 5 provided the measured levels of tracer gas; the total doses are shown in the boxes (Table 1).

The spatial distribution concentrations are dispersed and, comparing theoretical and measured data, they are all similar, except for close to the contaminant emission, where there is higher concentration.

To illustrate the effectiveness of the ventilation solution, Smith applied the industrial hygiene concept of ‘effective flow’ VEFF, although he noted that ASHRAE uses the inverse of this, the Ez Factor, to evaluate air distribution effectiveness in a room. The two terms are consistent and enable the calculation of an effective air change rate (ACR). So in Case 1, ACR was 3.4, which compares reasonably to the actual supplied ACR’ of 4.1 (Figure 3 and Table 1).

He then removed the mixing fan and, making no other changes, repeated the test to provide results as shown in Table 1. 

This indicates a different situation where, although ‘mixing diffusers’ are used, there is no uniformity in mixing and the effective air change rate is 1.5 – just 37% of the supplied air change rate of 4.1. Aside from the near field (S5), the most concerning result was that point S1 received a very high dose.

A training centre used by Smith’s organisation was tested as a real application. The highest dose (of 62 compared with the average of 36) was experienced by those sitting underneath the exhaust point, which also compared unfavourably with the theoretical dose rate of 13. Everyone in the room would have been exposed at a higher level than had been theoretically predicted (that was likely due to stratification). 

Smith’s full presentation includes more examples showing startling spatial differences in contaminant concentrations and doses linked to the respective positions, flowrates and geometries of supply and extract points.

View the presentation (at a cost) at bit.ly/CJASHTS23

The post A well-mixed cocktail? Air contaminant levels appeared first on CIBSE Journal.

Upper-air disinfection using ultraviolet-C (UV-C) light proved highly effective during tuberculosis outbreaks years ago, so it is no surprise that the industry turned to this technology again during the pandemic. 

Robotic equipment with germicidal ultraviolet light is becoming more popular in hospitals to provide an extra layer of disinfection after surface cleaning during room turnover, and is used in air handling units to disinfect the supply airstream. It was employed in a new and innovative way to solve a critical problem during the pandemic; UV-C light was used by some institutions to mitigate the personal protective equipment (PPE) shortage by allowing for re-use of PPE. 

This heightened public awareness of the disinfecting properties of UV-C, leading to many new products being introduced to the market and several existing products gaining a resurgence in sales. 

Different wavelengths of light have different efficacies of disinfection and different risks for human exposure, yet are often marketed in the same manner. Facility staff should consult a trusted adviser who understands the range of products available, and who can guide them through the pros and cons of various methods and equipment, work through specific needs, and ensure these are met. 

The CIBSE guide Covid-19: Air cleaning technologies (bit.ly/CJCIBCovid) allows users to assess the variety of air-cleaning devices currently on the market, and to discover which, if any, will reduce transmission risk in a given space effectively. Evaluating marketing claims requires diving into the data and published research, to decipher which applications lend themselves to which technology. 

Flexibility

The pandemic also highlighted the need for flexibility. A shortage of patient rooms designed for airborne infection isolation and critical care forced hospitals to repurpose standard medical-surgical rooms and revamp protocols. Critical care patient rooms require higher illumination levels on the patient bed than standard patient rooms. The new trend for adaptable patient rooms means that these rooms must be designed with higher illumination capabilities. Fortunately, LED lighting permits easy and smooth dimming to accommodate this flexibility. 

Traditional patient rooms have multiple zones of switched lights. Moving to an environment where the lights are dimmable gives patients and staff greater light control, allowing illumination to be tuned to the specific needs of the person and of the task being performed.

Telemedicine

The third shift is the expanded use of telemedicine, such as video conferencing, which increased at the onset of the pandemic. As the medical community evolved for telemedical visits, lighting specialists worked to develop best practices and new guidelines for video conferencing. By understanding the principles of key light, fill light and background luminance, as well as flicker mitigation and colour rendition, lighting designers can enhance the experience and effectiveness of telemedicine.

Circadian-supportive lighting design

One trend in healthcare facilities that is not a consequence of the pandemic, but of research, is circadian-supportive lighting design. 

Natural circadian rhythms are slightly longer than 24 hours: it is light (and dark) that maintains circadian rhythms on a 24-hour cycle. They can be impacted by five lighting factors: intensity (amount of light), spectral power distribution (wavelength), duration (length of exposure to light), timing (time of day when light exposure occurs) and light experience (accustomed personal exposure to light). More than one-third of the human genome is controlled by circadian rhythms, and more than half of all the drug-response pathways are clock-controlled. 

In hospitals, dynamic lighting systems that simulate nature’s day-night cycle have proven to be beneficial to patients and healthcare providers. Nightshift workers are at high risk of circadian disruption.

Our body produces cancer-fighting T-cells at night while we sleep. Newborn babies are getting their circadian stimuli through the environment instead of in utero, through their mother’s hormones. Lighting is no longer just about visual performance: its physiological impact on our bodies is equally as important.

Implementing the latest lighting technologies and market trends helps create the most supportive healthcare environments for patients, visitors and staff. 

The post Lighting’s critical role in healthcare appeared first on CIBSE Journal.

Activities such as cooking and cleaning can produce high pollutant concentrations, with potential impacts on human health, including respiratory and cardiovascular diseases^2,3. However, environmental regulation still focuses on outdoor air quality, with the exception of specific occupational exposures⁴.

A joint project between the universities of York, Chester and Nottingham has studied the production of different chemicals during cooking and cleaning. The Impeccable (Impacts of cooking and cleaning on indoor air quality: towards healthy buildings for the future) project used state-of-the-art equipment, coupled with computational modelling¹¹ to understand the complex underlying chemistry that occurs during and after domestic cooking and cleaning activities.

The study recommends the most effective ventilation strategies to reduce the air pollution created by cooking and cleaning.

The climate emergency has forced us to think more carefully about energy efficiency. Buildings are becoming increasingly airtight, but we have the potential to increase our exposure to indoor air pollution if sources such as cooking and cleaning dominate our personal exposure to air pollution.

Measuring VOCs while cooking in the home lab

We need to understand the sources and reactions of pollutants indoors, particularly as an increasing weight of evidence shows that secondary pollutants are more harmful to health than primary emissions⁹. For instance, the carcinogen formaldehyde is a reaction product of limonene oxidation, the latter species being a key component of many cleaning formulations¹⁰.

Cooking generates high concentrations of particulate matter (PM), nitrogen oxides (NOX) and carbon monoxide (CO). Emission rates depend on the cooking method, and oil and food types.

Emissions of PM are higher for frying than boiling and steaming, and higher when you fry meat compared with vegetables². During cooking, PM concentrations can reach several hundred mg/m³, particularly when frying², exceeding acute health standards over several hours⁵. Cooking can also generate ultra-fine particles (< 100 nm in diameter), which are associated with adverse effects on the respiratory and cardiovascular systems⁶.

Cleaning is another regular activity indoors, with bleach cleaning having a large impact on gas-phase and surface chemistry⁷. The prevalence of asthma among domestic cleaning staff suggests that cleaning activities may cause adverse health effects⁸.

The Impeccable project

The experiments undertaken range from benchtop ones in a lab to determine specific emission rates from individual products or processes, through to more realistic settings, where full meals are cooked in a more home-like environment.

Measurements are taken using on- and off-line diagnostics, to determine types and quantities of various indoor air pollutants. Selected-ion flow-tube mass spectrometry (SIFT-MS) was used to measure real-time concentrations of more than 40 volatile organic compounds (VOCs) during the cooking and cleaning experiments.

This technique uses a plasma to generate ions, which then ionise VOCs present in the sample gas¹². These charged species are then separated and quantified based on their mass-to-charge ratios. An example of the real-time data obtained during a cooking experiment is shown in Figure 1.

The modelling of indoor air chemistry has been carried out using INCHEM-Py, an open-source box model that uses a detailed chemical mechanism, combined with parameterisation for indoor-outdoor exchange, gas-particle partitioning, surface deposition, and internal photolysis¹³.

The detailed model allows us to simulate the time-evolved concentrations not only of the species emitted from indoor activities, but also of those formed after chemical reactions, such as formaldehyde, peroxyacylnitrate species (PANs) and PM.

The simulated concentrations of some secondaries formed after the typical stir-fry cooking experiment are shown in Figure 2. These products are often more harmful to human health than the original emissions, so understanding how they are produced can help inform scientifically rigorous mitigation measures (such as extraction of cooking fumes or increased ventilation).

Relevance for building design and operation

Kitchen ventilation is regulated by Approved Document F of the Building Regulations in England. In new houses, there is a requirement for a cooker hood that extracts to the outside or a wall-mounted fan.

The advantage of the cooker hood is that it captures cooking contaminants before they mix in the kitchen, whereas the wall fan allows the contaminants to mix before they are extracted. The required flowrate through the hood is half that of the fan, which implies that it should capture 50% of all emitted contaminants. This is known as a capture efficiency. There is no requirement to test hoods to make sure they meet this requirement, although there is now an ASTM standard¹⁴ that tests some types of hood in a laboratory environment. Future versions of Approved Document F should require cooker hoods to conform to the ASTM standard or allocate a punitive capture efficiency to those that are untested.

Ventilating for 10 minutes after cooking has finished has a significant effect on exposure and should be recommended by public health campaigns^15,16. The higher airflow rate through the wall fan means that it reduces the concentration of contaminants in the air faster than the hood. So having multiple flowrate settings on a hood is advantageous. The best place to locate a hood is against a wall, between cabinets, directly over the gas burners/hob, and as close to the burners as the manufacturer allows. Noise is often a barrier to their use, so using short, wide, straight, rigid, noise-absorbing ducts that reduce air velocity to 2-3 m/s is best practice.

When cooking, using the back burners increases the pollutant capture efficiency¹⁶. Consider using the hood, at least on low speed, for general kitchen ventilation when using other appliances, such as toasters.

Using induction rather than gas burners, and electric rather than gas ovens, reduces the emission of nitrogen dioxide (NO₂), but the chronic harm from exposure to NO₂ is significantly less than that from fine PM. A good cooker hood will capture NO₂ from a burner, so using the hood is more important than changing from a gas to an induction stove.

In very airtight homes (<1 m³/h/m²) make-up air into the kitchen or home is needed and this can be provided using mechanical ventilation with heat recovery (MVHR). Reclaiming thermal energy from the exhaust stream can be problematic in MVHR systems because grease can clog the heat exchanger. This problem has yet to be solved and may require more frequent cleaning of filters.

Some homes have recirculating fans, which pass air through a particle filter and resupply it into the kitchen, rather than exhaust it outside. In this instance, it is imperative to use induction hobs. Electric hobs have their own complications because they can emit PM when they get dirty. For homes that have no fans in their kitchens, windows and doors should be opened when cooking and cleaning to provide ventilation in the short term. In the medium term, a mechanical system should be installed and trickle ventilators kept open at all times.

We would like to thank EPSRC for funding for the Impeccable project (EP/T014474/1).

About the authors
Professor Nicola Carslaw is professor of indoor air chemistry in the Department of Environment and Geography at the University of York

Dr Helen Davies is research associate in chemistry in the Department of Environment and Geography at the University of York

Dr Benjamin Jones associate professor in the Department of Architecture and Built Environment at the University of Nottingham.

References

1. Nazaroff, W. W.; Goldstein, A. H., (2015), Indoor Air, 25, (4), 357-61
2. Abdullahi, K.L. et al. (2013), Atmos. Environ. 71, 260-294
3. Wolkoff, P. (2013) Int. J. Hygiene Env. Health, 216, 371-394
4. Weschler, C.J., and N. Carslaw, Environ. Sci. Technol., 2018, 52, 2419-2428
5. Logue, J.M., et al. (2011), Indoor Air, 21, 92-109
6. Rim, D. et al. (2013), Environ. Sci. Technol., 47, 1922-1929
7. Wong, J. P. S et al. (2017) Indoor Air, 27, 1082-1090
8. Medina-Ramón, M. et al. (2006) Occupational and Environmental Medicine, 62, 598-606
9. Buchanan, I.S.H. et al. (2008), Indoor Air 18, 144-155
10. Wang, C., M., et al. Environ. Sci. Proc. Impacts, 2017, DOI: 10.1039/C6EM00569A
11. Impeccable website: impeccable.york.ac.uk
12. Smith, D., Španel, P., (2005), Mass Spectrometry Reviews, 24, 661-700
13. Shaw et al. (2021). Journal of Open Source Software, 6(63), 3224, doi.org/10.21105/joss.03224
14. ASTM, Measuring Capture Efficiency of Domestic Range Hoods. Report. 2018.
15. Holgate S et al. The inside story: Health effects of indoor air quality on children and young people. Royal College of Paediatrics and Child Health; 2020.
16. O’Leary C, et al. Setting the standard: The acceptability of kitchen ventilation for the English housing stock. Building and Environment. 2019:106417.

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Air purification or cleaning devices have been discussed as a solution, as they provide a localised and decentralised means of ventilation without the need for large plant and distribution systems.

Leeds Beckett University’s Lewis Turner investigated the performance of air purification systems to reduce infection. His paper, Efficacy of air purification to control infection in NHS hospitals, looked to benchmark air purifiers against currently used mechanical and natural ventilation techniques within an NHS hospital ward scenario (as shown in Figure 1). Last month, the paper was runner-up in REHVA’s student competition.

In Turner’s scenario, there are four males on the ward: person one is infected with a respiratory virus and has symptomatic coughing, while the others are not infected but are susceptible to infection.

Two air purifiers (AP) were studied, one representing a ‘healthcare grade’ system and the other a ‘domestic’ system (as shown in Figure 2). The healthcare air purifier (AP-H) had a ‘side in, top out’ flowrate of 520 m³.h^-1 and a maximum aerosol efficiency of 99.728%. The domestic air purifier (AP-D) had a maximum flowrate of 190 m³.h^-1 and maximum aerosol efficiency of 99.82%. In the scenario, the air purifiers were located on the floor, to the right of person one.

Lewis modelled the risk of infection and developed a computational fluid dynamics (CFD) model to investigate the pathogen airflow characteristics, benchmarking the APs against the mechanical and natural ventilation systems. The mechanical ventilation ductwork system in Figure 2 provides balanced ventilation of six air changes per hour with a volume flowrate of 528 m³.h^-1. The natural ventilation was provided through the openable windows and with average wind speeds and window opening, the study used an average fresh airflow rate of 185 m³.h^-1.

The infection risk mathematical modelling calculated the probability of susceptible people catching an infection when in the same ventilated space as infectious people. The CFD study simulated cough particulates travelling through air and how they interacted with the ventilation systems. Person 1 was simulated sitting up in bed, coughing 3.13 e^-8kg of Covid-19-infected aerosol into the zone within a period of 0.5s at 90º to their face, with a velocity of 10m.s^-1 from a 4cm² mouth positioned 590mm above the bed. Cough particulate had a randomised diameter of between 2.5mm and 200mm, consisting of liquid water. The natural ventilation was not simulated because of the chaotic nature of the airflow.

Around 85% of visits to emergency departments are less than four hours long, so the study focused on the number of subsequently infected patients under typical circumstances, across a four-hour period.

The infection risk mathematical modelling results, shown in Figure 3, indicate similarities in performance of AP-D and natural ventilation, with a performance differential of 10.7% in favour of AP-D. AP-D and natural ventilation have a comparable flowrate, but have different mixing factors of 2 and 2.5 respectively. The mixing factor has a significant impact on performance because it defines how well fresh air dilutes the pathogen. This impact is higher for natural ventilation because of unpredictable natural airflow currents, which cause ineffective mixing. For AP-D, the airflow (treated and supplied by AP-D) is directed into the zone at a constant level and can mix effectively with the internal air.

The study identified that the higher mixing factor for the APs results in a 29% higher infection probability, with the lack of fresh air supply contributing to the poor performance of the air purifiers to control infection. Both APs dilute pathogens with greater performance than natural ventilation.

The CFD study generated three sets of data, two of which are shown in Table 1. These indicate that mechanical ventilation has the highest performance. The APs do, however, present some efficacy for infection control as they reduce the particulate mass to 5% in less than 13 seconds (mechanical ventilation can reduce it to 5% in 4 seconds). All ventilation systems fail to remove a majority of the infectious particulate, which means much of the particulate is still present on walls and surfaces, and can sustain for multiple days, depending on the material.

Figure 4 presents the third set of data from the CFD simulation – the maximum penetration distance of particles within the zone from person 1. The data has been compared with the distance of each susceptible person to identify if particles could potentially come into contact with them. It is assumed that 1.25e^-9 kg of particulate mass represents an infectious load of Covid-19, so greater than 1.25e^-9 kg indicates a higher infection risk and less than 1.25e^-9 kg indicates a lower infection risk. Overall, mechanical ventilation has the highest performance, with only one susceptible person potentially inhaling an infectious load. There were three potential infectious-load inhalations for AP-H and two for AP-D.

The results identified that all ventilation systems fail to effectively remove infectious particulate from the zone, with most of the particulate that remained found on the ward’s walls and surfaces. Particles become scattered and, consequently, miss the intake to the APs and contact the air purifier body and surrounding surfaces.

These findings indicate that the size of intake to each system impacts the total escaped mass – and as the air purifiers have a smaller particle extraction capture area, they cannot remove as much mass as the mechanical ventilation system.

The results identified that AP-H and AP-D fail to control the penetration of infectious particulate effectively, whereas the mechanical ventilation system can control particulate with much higher effectiveness.

This issue seems to be amplified by the low position of the air purification devices, as the supply from the APs is much closer to the injection point than the AP intake. As the particles move to be drawn in by the AP, they are likely to be impacted by the turbulent upward airflow from the AP. Additionally, the short-circuiting between AP intake and supply can reduce their efficacy, as further penetrated particles cannot be drawn into the APs. This does not occur in mechanical ventilation because of the effective air distribution throughout the zone.

AP-H is found to exceed the performance of AP-D throughout the infection probability modelling, and the CFD results seem to corroborate these results.

Lewis concludes that these air purifiers have a higher performance than natural ventilation and should be considered for hospitals where mechanical ventilation is not available. However, he notes that air purifiers cannot perform to the level of standard mechanical ventilation, so should not be used as an alternative.

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Led by Loughborough University, the ‘Airbods’ project is a collaboration of academic institutions and engineering research firm Wirth Research, and made a vital contribution to the government’s Events Research Programme (ERP), which evaluated the transmission risk at big events.

Standing for ‘Airborne Infection Reduction through Building Operation and Design for SARS-CoV-2’, the Airbods project’s high-resolution CO₂ monitoring and modelling informed the government’s decision in July 2021 to resume the normal operation of large events in culture, music and sports industries while improving venue safety.

Praising the outcome of the Airbods project, the awards judges said: ‘The research has resulted in usable guidance and tools to help designers identify and mitigate infection control risk. It has enabled policy-makers and stakeholders to evaluate the changes in risk that modifications to ventilation rates, occupancy density, and exposure times have at a population scale, so that interventions can be better focused.’

The Airbods project began in March 2021, when the government’s Engineering and Physical Sciences Research Council (EPSRC) issued a call for rapid responses for funding. Most of the participants in the Airbods project team had worked with each other before on ventilation and indoor air quality projects and publications, while a small number of the group had been meeting every week during the pandemic to discuss and share ideas about how they might respond to what had become a global pandemic with far-reaching economic and social impacts.

The team included specialists from academic institutions including University College London (UCL), University of Nottingham, University of Sheffield, University of Cambridge and London South Bank University.

The Airbods project informed the government’s decision to resume the normal operation of large events in culture, music and sport

The Airbods team was asked to contribute to the ERP by carrying out the environmental study of a wide range of venues and events between April and July 2021. This part of the programme, led by the UCL team helped to build the evidence based on air quality and improved understanding of potential risks of airborne transmission, and their mitigations.

Malcolm Cook, Professor of Building Performance Analysis at Loughborough University, led the Airbods programme. ‘It has been a privilege to lead such a committed and experienced team,’ says Cook. ‘The collaboration across the project partners was highly focused from the start: it was exciting but very intense. The whole team worked exceptionally hard and the experience couldn’t have been better in terms of teamwork and commitment at a time when many people had personal challenges of their own. Our team of eager, early career researchers certainly got more than they bargained for when they willingly accepted the challenge to prepare hundreds of sensors and loggers for installation into some of the largest, most complex entertainment and sports venues in the UK!’

Working rapidly to develop evidence for the ERP, the University of Nottingham team developed analytical models to estimate the risk of SARS-CoV-2 long-range aerosol transmission indoors at both individual and population scales. A ‘relative exposure index’ estimated the relative inhaled doses in a comparator and reference scenario in the presence of an infected person.

The index was used as evidence by the UK Scientific Advisory Group for Emergencies (SAGE) Energy Modelling Group, and forms the basis of the CIBSE COVID-19 Relative Exposure Calculator released with CIBSE’s COVID-19: Air cleaning technologies documents. This tool enables building operators and consultants to assess the effectiveness of ventilation and air-cleaning interventions at reducing risks in their own particular scenarios.

An extension of Airbods work considered the population-scale effects of ventilation in indoor scenarios, enabling policy-makers to evaluate the changes in risk that modifications to ventilation rates, occupancy density, and exposure times have at a population scale. This allows potential interventions to be better focused.

Cook, who has been working in ventilation modelling and measurement for around 30 years, says that, prior to Covid-19, it had been difficult to engage people’s interest in the importance of indoor air quality. ‘Its invisibility means it is often overlooked,’ he said.

‘However, when the pandemic hit, everybody wanted to talk to us about how to improve their pubs, restaurants and other entertainment venues. Our computer simulation gave us the means of visualising what was going on and, for instance, creating graphics, animations and computer models that could show people the impact of people breathing out moisture particles with virus on them in different scenarios.’

The Airbods project’s initial phase was fast-moving, Cook says, which was itself a challenge. ‘Within two weeks, the team had completed risk assessments and secured ethical clearance as well as purchased and calibrated hundreds of sensors, and rolled them out into the field, while ensuring the computer interfaces were working as they should.’

Between April and July 2021 pilot events were monitored in indoor and outdoor settings, with variations of seated, standing, structured and unstructured audience styles, and a range of participant numbers.

These included the World Snooker Championships at the Crucible in Sheffield,  The FA cup and the EURO2020 football events at Wembley Stadium, London, and the BRIT Awards at the O2 in London.

The team used wireless technology to encrypt, transmit, and cloud-store the data, measured by sensors sampling environmental variables at two-minute intervals. This enabled real-time data analysis, while the team used the live information to respond rapidly to any data disruption and to correct errors and malfunctions. The team also comprised specialist microbiologists who conducted simultaneous microbiological sampling to provide information on the types of areas and surfaces in which it is most likely to encounter bacterial contamination.

Every week, the Airbods team would meet government bodies, the DCMS and BEIS to share results and discuss upcoming tests, while feeding their findings back into the next round of tests. ‘It was very fast moving, compared to typical academic research, but very exciting. We produced outputs in a very short period of time, reporting on each event as it happened. The final government report brought it all together, with our work undertaken alongside other organisations monitoring other aspects of the events, such as crowd dynamics and so on.’ Around 20 people from the Airbods team were involved in the research, with around 40 other participants.

Measuring CO₂ as a surrogate for the virus revealed that many buildings aren’t ventilated well enough, Cook says. ‘One of the key findings was that if buildings were ventilated as they should be, then the risk of transmission was relatively low. The problem we found was that many buildings weren’t ventilated as intended and may not have taken into account occupancy patterns throughout the building.

CIBSE guidance is for airflow of around 12 L·s^–1 per person – if that level of ventilation was present, then we may not have had the level of transmission that we suffered. The problems were because we had poorly ventilated, poorly operated, and poorly maintained spaces.’

Cook explains that building owners and operators didn’t always know how the ventilation system was intended to operate most effectively and, related to that, some systems were poorly maintained and weren’t delivering what the design intended. He says the team was surprised to find that transmission potential was found even at outdoor events. ‘At Wembley Stadium, for instance, we were finding high CO₂ levels on the terraces as well as around the bar areas and toilet queues, indicating a risk.’

A series of pilot events were monitored, including Royal Ascot and major football events at Wembley Stadium, left

The main recommendations for reopening were, therefore, to limit capacity, maintain testing and physical spacing for the bar area indoors, and to reduce all ventilation recirculation of air to zero, using only fresh air ventilation. Cook acknowledges that post-pandemic, ‘Covid-fatigue’ has started to see general interest in the subject starting to wane, particularly with government moving on to other issues. However, he says: ‘I don’t think it will ever disappear from the minds of our engineering fraternity. Architects and building designers will remain interested in how they can make their buildings healthier for a long time.

‘Healthy buildings and wellbeing are still very much on the agenda, and it’s up to organisations such as CIBSE and its members to keep it there.’

The Airbods team is still active, and, as well as working on a number of papers on the research project for publication in academic journals and contributing to new guidance, it will be running events in conjunction with CIBSE.

The team is preparing a bid for more funding, broadening its scope to cover topics including wellbeing, intelligent buildings and energy consumption – looking at how safe environments can be provided in an energy efficient way. ‘The project will enable us to undertake more experiments and computer modelling to gain a deeper understanding of how air flows and interacts with people in buildings.’

Airbods’ contribution during Covid-19 is not only of academic interest – the intention is to help inform the future. ‘All the modelling and monitoring we’ve done have been geared to understand how we can do better in the next pandemic,’ Cook says.

‘Also, crucially, it’s about making buildings healthier – how can we better design, use and operate buildings to minimise absences due to viral infections.’

More findings and guidance on infection resilience: https://airbods.org.uk 

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