The Effectiveness of Green Building Assessment Tools in Evaluating Building Hygienic Requirements
Tony Ip 葉頌文/ Ivana Luk 陸椅雯
Building performance and occupants’ health are the two most important design considerations for all buildings. They are affected by the form of the building and the materials used. This article delineates the effectiveness of current green building assessment tools and considers if such tools can be successful in publicising green building design and preventing hazards related to water and hygiene. It evaluates the requirements of different global assessment tools, such as LEED, WELL and BEAM Plus, and their responses to social, environmental and economic conditions. It also notes that while assessment tools typically share similar concerns for the control of indoor environmental quality, they vary in their level of rigour. The comparison shows the need for improvements in the current rating system and so for the need of a better framework for hygienic and sanitary requirements in buildings.
To address the issue of sustainability, various green building assessment tools have been implemented worldwide to improve building performance, human health and the built environment. LEED (Leadership in Energy and Environmental Design) is one of the most commonly used green building rating and certification systems. It prioritises material selection, human comfort and air quality. WELL Building Standard is another popular assessment tool. It prioritises health and wellness in the design and construction processes, particularly through researching and consulting with different stakeholders. BEAM Plus is more commonly adopted in Hong Kong. It focuses on site, materials, energy use, water use, indoor environmental quality and innovative features, aiming at reducing the environmental impact of buildings and improving occupants’ health. Primarily focusing on the evaluation of these three assessment tools, this article also discusses BREEAM, CASBEE and Green Mark where appropriate.
These assessment tools cover the same ground regarding energy efficiency, water conservation, environmental protection and the provision of a high-quality indoor environment. Their goal is to minimise the consumption of water, energy, materials and the production of waste and harmful emissions in the construction process.
Occupants’ comfort and a building’s hygiene are strongly correlated. The practice of maintaining a sanitised indoor environment can keep occupants healthy. In this article, we evaluate the hygiene requirements of the different green building assessment tools we consider. Specifically, we ask whether they adequately help produce buildings that allow for maintaining good health and preventing disease. The main factors that determine the relationship between green buildings and hygiene are material selection (hazardous emissivity, physical properties, chemical properties), water usage (water leakage, potable water) and building design (daylight availability, indoor air quality, temperature).
With regard to the use of materials, various harmful pollutants, such as formaldehyde, are often found in building materials and easily emitted during both the construction and operation phases. Building materials, primarily hardwood, plywood, laminated floorings, adhesives, paints and varnishes, are also major contributors to indoor emission of volatile organic compounds (VOCs). Many studies have shown that indoor concentrations of pollutants may pose high risks to human health, such as cancer¹. Green building assessment tools have established standards to eliminate such hazards by reducing the amount of indoor air pollutants in an indoor environment. Currently, LEED restricts the use of mercury in thermostats, switching devices and lamps, as well as urea-formaldehyde and heavy metals in plated finishes. WELL limits asbestos, lead, polychlorinated biphenyl abatement and mercury, as well as toxic materials such as perfluorinated compound, flame retardant, phthalate, isocyanate-based polyurethane and urea-formaldehyde. BEAM Plus restricts the use of non-environmentally friendly materials such as CFC and PVC. Other green building assessment tools, such as BREEAM, require that products specified at the design stage and installed in the post-construction stage are covered by environmental product declarations, and Green Mark restricts the use of high-emitting building and furnishing materials.
Other than indoor pollutants, microbial activity can have a significant impact on building materials, affecting everything from a building’s durability to occupants’ health. Air, water and surfaces are the primary indoor microbe reservoirs. Microbes typically enter the indoor environment either from people or from and air or water leakage². They are mostly found in moist areas, such as a building’s plumbing systems. Indoor humidity influences airborne survival, while the virulence of infectious agents and the prevalence of moist surfaces cause mould growth³.Building surfaces and human-to-human contact via shared objects often serve as the path for microbes’ exchanges. Not many green building assessment tools provided strategies for the control of microbial impacts. Only the WELL Building Standard stipulates antimicrobial processes for surfaces. It states that all countertops, fixtures in bathrooms and kitchens, handles, doorknobs, light switches and elevator buttons must either be coated in or composed of a material that is abrasion-resistant, non-leaching and meet local environmental authority testing requirements or be regularly cleaned with a UV cleaning device.
When it comes to visual comfort, daylight is important. Research suggests that artificial lighting can have negative impacts on human health, while daylighting can improve productivity, maintain physical health, and improve mental health by reducing sadness associated with seasons’ affective disorder⁴. Daylight is not only healthy but also environmentally friendly. For example, new nano technologies utilise diffuse daylight to generate renewable energy and improve air quality. Air Improvement Photovoltaic (AIPV) systems can produce solar energy from daylight through cadmium telluride nano thin-film photovoltaic technology. The self-cleansing quantum-dot nano-top coating systems can also be applied to decompose PM2.5 and volatile organic compounds. Most green building assessment tools suggest buildings provide individual lighting controls and maintain an illuminance level between 300 lux to 3000 lux from 9 am to 3 pm. The WELL Building Standard additionally specifies recommended desirable illuminance levels. Strategies for doing so include interior (automated) window shading or occupant-controlled blinds, external shading systems, variable opacity glazing such as electrochromic glass, interior light shelves and micro-mirrors that can reflect sunlight toward the ceiling.
Having the right temperature and humidity levels is crucial for health. Low humidity and temperature levels can allow viruses to persist, while overheated indoor space is correlated with ‘sick building syndrome symptoms’ such as irregular heart rates, respiratory issues, fatigue and negative moods⁵.High humidity is also associated with mould and fungal growth. In order to maintain a high level of thermal comfort, green building assessment tools require a high level of thermal comfort in compliance with either ASHRAE Standard 55 – 2010 or the relevant ISO and CEN Standards, along with the provision of individual thermal comfort controls such as operable windows. The WELL Building Standard requires the installation of either hydronic radiating heating and cooling systems or electric radiant systems due to evidence that radiant systems can provide better comfort and other benefits than conventional air systems⁶. BEAM Plus, in contrast, simply specifies the need for operable windows or doors. Other assessment tools such as CASBEE suggest the use of separate air conditioning systems for perimeters, interiors and other relevant circumstances.
Studies show that poor indoor air quality can lead to serious health problems, including Legionnaires’ disease⁷, lung cancer and carbon monoxide poisoning, as well as contributing to other common health issues such as allergies, asthma, colds and other infectious diseases. Hence, it is important to maintain a balanced supply of indoor and outdoor air. Other studies have shown that increases in building ventilation are associated with the reduction of sick building syndrome symptoms⁸. With respect to indoor air-quality performance and naturally ventilated spaces, most green building assessment tools require compliance with ASHRAE Standard 62.1 – 2010 or CEN Standards EN 15251 – 2008 and EN 13779 – 2007, as well as to provide ventilation rate monitor and filtration. LEED specifically recommends sufficient exhaust and ventilation systems using integrated particle filters or air-cleaning devices for entryway systems. Such systems can include installing grates and pressurised entryway vestibules at high-volume building entrances for health care facilities. WELL requires that relative humidity levels be kept between 30% and 50% at all times, and air quality to be maintained through isolation and proper ventilation of indoor pollution sources and chemical storage areas. The provision of dedicated outdoor air systems, advanced air purification through carbon filtration and air sanitisation such as ultraviolet germicidal irradiation, photocatalytic oxidation and air quality maintenance are also deemed essential. BEAM Plus specifies the importance of having sufficient permanent openings to allow natural ventilation. CASBEE suggests a centrally controlled air-mixing system with a ventilation rate that satisfies the SHASE-S102-2003 Ventilation Standard, whilst Green Mark recommends providing ultraviolet germicidal irradiation (UVGI) systems to control airborne infective microorganisms and using high-efficiency filters in ventilation systems.
A well-thought out sustainable design should keep unwanted water away. Building materials subjected to excessive moisture may undergo changes in their physical properties, potentially causing mould growth or other forms of contamination⁹. Not all of the green building assessment tools have guidance on minimising the risk of water leakage. BEAM Plus requires that buildings install water leakage detection and alert systems in all municipal potable water-tank rooms. BREEAM also requires buildings to implement leak detection systems and flow-control devices that regulate water supply.
In terms of potable water, more green building assessment tools show concerns for the efficiency of water delivery than the quality. Water can be contaminated by lead, arsenic, glyphosate, atrazine and microbes which may pose serious health threats. Exposure to organic contaminants such as polychlorinated biphenyls (PCBs) and vinyl chloride in drinking water is associated with a range of severe health problems, including cancer, immune deficiencies and nervous system difficulties. BEAM Plus requires water quality be fully compliant with the Hong Kong Drinking Water Standards and for proper cleaning and maintenance of water-storage tanks. The WELL Building Standard limits certain disinfectants, disinfection by-products and fluoride in drinking water in order to mitigate fluorosis, stomach discomfort, and eye and skin irritation. It also requires periodic water-quality testing and remediation, the implementation of water-treatment systems using carbon filters, sediment filters and UV sanitisation, and the provision of enough water dispensers to allow building occupants to stay hydrated with high-quality water.
A building that is green does not mean it is hygienic. The open office arrangement that is common in corporate building design is a good example. The lack of physical barriers allows better use of daylighting, but a recent investigation published by South Korea’s Centres for Disease Control proved that crowded office spaces accelerated the spread of virus, citing one case where 94 out of 216 employees were infected¹⁰. The close proximity of furniture and the number of shared spaces and surfaces, such as door handles and pantries, all have implications for the spread of disease. Another example is the use of bio-based green building materials. Studies have found that they are more susceptible to moisture damage and fungal growth than conventional building materials. However, moisture susceptibility is still not a major assessed element for many such green building materials, leading to the occurrence of mould and so to mould-related minor health conditions¹¹.Damp building materials may also be associated with respiratory-based diseases, for example by exacerbating the problems of people with asthma¹².
Alarmingly, none of the green building standards and guidelines have anything but limited measures aimed at preventing epidemics. Some existing measures may help restrict the spread of harmful viruses or bacteria but they are not sufficient. Studies of Covid-19 will create opportunities to update assessment tools. For example, the finding that the novel coronavirus lasts longest on plastic and stainless steel, and shortest on cardboard and copper gives a new understanding as to what materials should be used to create a healthier environment. The guidance published by the World Health Organisation on water, sanitation and hygienic conditions to prevent the spread of the contagious disease also sheds light on the application of the household water-treatment technologies to reduce virus transmission, and should also be incorporated into green and healthy design. The WELL Building Standard was amongst the first to identify strategies that can help prevent community transmission of Covid-19, among them installing large sinks, using disposable soap containers and hand towels, implementing rigorous cleaning protocols for all high-touch surfaces, and providing of adequate air ventilation and filtration.
Short-term remedy and long-term measures should be introduced to cope with epidemics in a more holistic way. Existing buildings should be quickly provided with soap and hand sanitisers, frequent surface sterilisation using antimicrobial agents, hand-free lights, doors and elevators, easy-to-disinfect surfaces, protective covers where necessary and ultraviolet light irradiation via lamps or sunlight, separate wet and dry walking areas for gyms and swimming pools. Other long-term measures including but not limited to, the introduction of advanced air-distribution systems, the limitation of moisture accumulation and so of potential mould growth, the provision of high-quality water systems, resources for remote-work ergonomics and the development of emergency management plans. More advanced measures could be gradually incorporated into existing guidelines. For instance, schemes could be developed that provide quick access to medical facilities, create flexible layouts that allow rooms to be swiftly transformed into medical facilities, transitional residential spaces or isolation and observation wards, or put in place water seals that can reduce the risk of virus transmission through drainage pipes.
Overall, the pandemic is a warning that that more hygiene-related measures should be integrated into green building design, and that green environmental assessment tools should be revised not only for the sake of the environment but also to ensure better hygiene and health.
Tony Ip is founder of Tony Ip Green Architects (TiP). He is a sustainable design architect and urban designer.
Ivana Luk is an architectural assistant of TiP. She studied Architectural Science at Ryerson University and is currently pursuing a Master in Architecture at the University of Toronto.
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Fig.1 AIPV canopy at CIC ZCP
Fig.2 AIPV canopy at CIC ZCP close up
Fig.3 AIPV canopy at CIC ZCP close up