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Healthy building refers to an emerging area of interest that supports the physical, psychological, and social health and well-being of people in buildings and the built environment. [1] Buildings can be key promoters of health and well-being since most people spend a majority of their time indoors. [2] According to the National Human Activity Pattern Survey, Americans spend "an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles." [3]
Healthy building can be seen as the next generation of green building that not only includes environmentally responsible and resource-efficient building concepts, but also integrates human well-being and performance. [4] These benefits can include "reducing absenteeism and presenteeism, lowering health care costs, and improving individual and organizational performance." [1]
Healthy building involves many different concepts, fields of interest, and disciplines. [5] 9 Foundations describes healthy building as an approach built on building science, health science, and building science. [6] An integrated design team can consist of stakeholders and specialists such as facility managers, architects, building engineers, health and wellness experts, and public health partners. Conducting charrettes with an integrated design team can foster collaboration and help the team develop goals, plans, and solutions. [7]
There are many different components that can support health and well-being in buildings.
Spengler considers indoor air quality as an important determinant of healthy design. [8] Buildings with poor indoor air quality can contribute to chronic lung diseases such as asthma, asbestosis and lung cancer. [9] Chemical emissions can be outgassed by building materials, furnishings, and supplies. Air fresheners, cleaning products, paints, printing, flooring, and wax and polish products can also be a source of volatile organic compounds (VOCs) and semi-volatile compound (SVOCs). The LEED v4 Handbook posits that indoor air quality is "one of the most pivotal factors in maintaining building occupants' safety, productivity, and well-being." [10]
Higher rates of ventilation affect indoor pollutants, odors, and the perceived freshness of air by diluting contaminants in the air. [11] ASHRAE's Standard 55-2017 has minimum standards of 8.3 L/s/person. In one study, raising the rate to 15 L/s/person increased performance by 1.1% and decreased sick building symptoms by 18.8%. [12] Whole Building Design Guide recommends separating ventilation from thermal conditioning so as to increase comfort. [13]
Natural ventilation is discouraged in buildings that have strict filtration requirements, contaminant dilution concerns, special pressure relationships, speech privacy concerns, and internal heat load demands. The San Joaquin ASHRAE chapter recommends assessing the outside air quality and configuration of the facade and building before demonstrating compliance and control of natural ventilation. ASHRAE Standard 55-2017 section 6.4 requires the natural ventilation be "manually controlled or controlled through the use of electrical or mechanical actuators under direct occupant control." [14] Chris Schaffner, CEO of the Green Engineer, describes operable windows as the "HVAC engineer's ultimate safety factor." [15] Spengler and Chen recommend natural ventilation being used wherever possible. [8]
Dust and dirt can be a source of exposure to VOC and lead as well as pesticides and allergens. High efficiency filter vacuums can remove particles such as dander and allergens that otherwise result in breathing issues. [16] A study of asthmatic children in inner city urban communities suggests they became sensitive to the presence of cockroaches, mice, or rats due to their presence in their homes. [17]
The US culture relies heavily on disposable products, especially within healthcare, to minimize on cost and time. In hospitals, for example, healthcare providers cut on costs associated with sterilizing equipment between patient cares by using ready-to-use disposable trays. However, this may at a cost to the environment; in one study, [18] disposable cotton towels were suspected to have an adverse environmental impact. It is estimated that cotton production requires 6.6 kg of carbon dioxide equivalents and 0.024 kg of nitrogen emissions, in addition to a substantial amount of water, fertilizer and work. Healthcare managers are urged to request transparency of medical product production (and waste management) lines to provide assurance that products used have zero or minimal impacts on human health and our environment.[ citation needed ]
Thermal comfort is influenced by factors like air temperature, mean radiant temperature, relative humidity, air speed, metabolic rate, and clothing. [19] Thermal conditions can affect learning, cognitive performance, task completion, disease transmission, and sleep. ASHRAE defines an acceptable thermal environment as one that 80% of occupants find acceptable, though individual occupant thermal control results in higher satisfaction of occupants. [20] Indoor spaces that are not air conditioned can create indoor heat waves if the outside air cools but the thermal mass of the building traps the hotter air inside. Cedeño-Laurent et al. believe these may become worse as climate change increases the "frequency, duration, and intensity of heat waves" and will be harder to adjust to in areas that are designed for colder climates. [21]
The Whole Building Design Guide recommends the indoor relative humidity to be between 30 and 50% to prevent unwanted moisture and to design for proper drainage and ventilation. [13] Moisture is introduced into the building either by rainwater intrusion, outside humid air infiltration, internally generated moisture, and vapor diffusion through the building envelope. [22] High temperatures, precipitation, and building age enable mold. [23] It contributes to mold and poor indoor air quality. Vapor retarders have traditionally been used to prevent moisture in walls and roofs. [22]
While noise is not always controllable, it has a high correlation and causation relationship with mental health, stress, and blood pressure. [24] One study suggests that there is a higher correlation of noise irritation and bodily pain or discomfort in women. [25] Effects of excessive noise pollution include hearing impairment, speech intelligibility, sleep disturbance, physiological functions, mental illness, and performance. The World Health Organization recommends creating a "National Plan for a Sustainable Noise Indoor Environment" specific to each country. [26]
Water quality can be contaminated by inorganic chemicals, organic chemicals, and microorganisms. [27] The World Health Organization considers waterborne diseases to be one of the world's major health concerns, especially for developing countries and children. WHO recommends following water safety plans that include management, maintenance, good design, cleaning, temperature management, and preventing stagnation. [28] Stagnant water is found to deteriorate the microbiological quality of water, and increase corrosion, odors, and taste issues. [29] The bacterial pathogen Legionella may have a higher potential for growth in large buildings due to long water distribution systems and not enough maintenance. [28]
Awareness of these issues is recommended by the WHO in order to maintain water quality:[ citation needed ]
Concerns of safety affect the mental and possibly physical health of residents by reducing the amount of physical activity. [30] Fear of crime can result in less physical activity as well as increased social isolation. Atkinson posits that crime is based on motivated offenders, targets, and the absence of guardians. Adjusting these in buildings may increase presumed safety. [31]
The type and timing of light throughout the day affects circadian rhythms and human physiology. In a study done by Shamsul et al., cool white light and artificial daylight (approximately 450-480 nanometers) was associated with higher levels of alertness. [32] Blue light positively affects mood, performance, fatigue, concentration, and eye comfort and enabled better sleep at night. [33] Bright light during winter has also been shown to improve self-reported health and reduce distress. [34]
Daylighting refers to providing access to natural daylight, which can be aesthetically pleasing and improve sleep duration and quality. [35] The LEED handbook writes that daylighting can save energy while "increasing the quality of the visual environment" and occupant satisfaction. [19]
Views to green landscapes can significantly increase attention and stress recovery. [36] They can also have a positive influence on emotional states. [37] [38] Ko et al. consider views to be "important for the comfort, emotion, and working memory and concentration of occupants." Providing a view to nature through a glass window may benefit occupants' well-being and increase employee's effectiveness. [39]
Creating a walkable environment that connects people to workplaces, green spaces, public transportation, fitness centers, and other basic needs and services can influence daily physical activity as well as diet and type of commute. [40] In particular, proximity to green spaces (e.g., parks, walking trails, gardens) or therapeutic landscapes can reduce absenteeism and improve well-being. [41]
Problems in foundations and underground conditions can have drastic impacts on the health of the building including structural issues such as cracking, humidity issues and indoor air quality and mould problems. These can arise from various factors. Different types of soil possess varying properties, and some can challenge foundation stability. Expansive soils like clay expand and shrink with moisture changes, causing foundation movement and settlement. Loose or poorly compacted soil can lead to uneven settling. Inadequate drainage around a building can lead to excessive soil moisture, exerting pressure on the foundation. This can result in movement, heaving, or settling. Large trees near a building can have extensive root systems that extract moisture from the soil, causing it to shrink and destabilize the foundation. Root growth can also apply pressure, leading to cracks or movement. Poor construction practices, including low-quality materials, inadequate reinforcement, or improper design, can compromise the foundation's structural integrity. Leaking or burst water pipes beneath the foundation can saturate the soil, destabilizing it and causing foundation movement or settlement. Earthquakes, floods, or storms can subject the foundation to extreme forces and vibrations, resulting in damage or shifting. Soil erosion due to heavy rainfall, landscaping issues, or improper grading can wash away supporting soil around the foundation, causing settlement or shifting. Extreme temperature fluctuations and freeze-thaw cycles can cause soil expansion and contraction, exerting pressure on the foundation and potentially leading to cracks or movement. [42] [43]
Especially the climatic effects are expected to worsen as climate change progresses. [44] Addressing foundation issues promptly is crucial to mitigate these consequences and maintain the safety, value, and integrity of the building. Monitoring solutions include ground penetrating radar and electrical resistivity tomography. [45] Protective measures include regular inspections and maintenance, good drainage and moisture control, appropriate ventilation and tending to trees and plants at the site. [42]
There are many aspects of a building that can be designed to support positive health and well-being. For example, creating well-placed collaboration and social areas (e.g., break rooms, open collaboration areas, cafe spaces, courtyard gardens) can encourage social interaction and well-being. Quiet and wellness rooms can provide quiet zones or rooms that help improve well-being and mindfulness. Specifically, a designated lactation room can support nursing mothers by providing privacy and helping them return to work more easily. [46]
Biophilic design has been linked to health outcomes such as stress reduction, improved mood, cognitive performance, social engagement, and sleep. [47] Ergonomics can also minimize stress and strain on the body by providing ergonomically designed workstations.[ citation needed ]
While some components of healthy buildings are inherently designed into the built environment, other components rely on the behavioral change of occupants, users, or organizations residing within the building. Well-lit and accessible stairwells can provide building occupants the opportunity to increase regular physical activity. [48] Fitness centers or an exercise room can encourage exercise during the work day, which can improve mood and performance, leading to improved focus and better work-based relationships. [49] Exercise can also be promoted by encouraging alternative means of transportation (e.g., cycling, walking, running) to and from the building. Providing facilities such as bicycle storage and locker/changing rooms can increase the appeal of cycling, walking, or running.[ citation needed ] Active workstations, such as of sit/stand desks, treadmill desks, or cycle desks, can encourage increased movement and exercise as well."Behavioral measures" can be taken to "encourage better public health outcomes: e.g., reducing sedentary behaviors by increasing access to stairways, using more active transportation options, and working at sit-to-stand desks." [50] Other examples that can promote health and well-being include establishing workplace wellness programs, health promotion campaigns, and encouraging activity and collaboration.[ citation needed ]
ASHRAE states that "Transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures." [51] Current recommendations include increasing air supply and exhaust ventilation, using operable windows, limiting air recirculation, increasing hours of ventilation system operation and upgraded filtration. [15] Joseph Allen of the Healthy Buildings Program at Harvard [52] [53] [54] suggests 4-6 air changes per hour in classrooms, especially when masks are off. [55]
Proper ventilation of areas has been found to have the same effect as vaccinating 50-60% of the population for influenza. [56] Enhanced filtration using a MERV 13 filter would be adequate to protect against transmission of viruses. [15] Allen mentions three ways humidity can affect transmission: respiratory health, decaying, and virus evaporation. Drier air also dries out the respiratory cilia that catch particles. Viruses decay faster between 40 and 60% humidity. [57] Respiratory droplets that become aerosols are less likely to do so at higher humidity. After 60%, mold growth begins to be encouraged. [58]
Sustainable design of patient rooms, intensive care units, and courtyards [59] could offer opportunities to not only maximize on human safety and wellbeing, but also environmental energy efficiency, waste management recycling, and performance optimization – all of which constitute the core of sustainability. However, this may come at an unexpected cost of enabling growth and spread of opportunistic microbes.[ citation needed ]
There are several international and governmental standards, guidelines, and building rating systems that incorporate health and well-being concepts: [60]
Founded in 1989, GreenSeal is a leading global ecolabeling organization (that is part of The Global Ecolabelling Network) that has set strict criteria for occupant health, sustainability, and product performance. [67] The Healthy Green Schools & Colleges initiative assists facility managers in locating low- or no-cost actions that have a significant impact on indoor air quality and health. The curriculum covers the full spectrum of facilities management methods and was created in collaboration with renowned school facility management professionals:[ citation needed ]
The WELL Building Standard Certification was first launched in 2014 (WELL v1), [68] and it focuses on the well-being and health of occupants in buildings. It was developed by Delos Living LLC and is currently administered by the International WELL Building Institute (IWBI) who released the second version (WELL v2) in 2020. [69] Generally speaking, WELL v2 [70] has updated requirements for investigating the relationship between building design and human health, adds more diversity to spaces and applications of the standard, and features a single rating system that resembles USGBC LEED's efforts.
More specifically, WELL v1 discussed 100 performance features that can be considered for the certification of a building. Those 100 performance features are classified into 7 "concepts" as follows: Air, Water, Nourishment, Light, Fitness, Comfort, and Mind. Of these 100 features, 41 were required preconditions, and 59 were optional optimizations. In order to achieve a WELL certification, a building has to meet the following:
On the other hand, WELL v2 uses a four-certification system that mimics LEED's scoring system. The required preconditions are decreased to only 23 (vs. 41 in v1), and the optimizations rose to 92 (vs. 59 in v1). WELL v2 also added 3 more "concepts": Sound, Materials and Community. With these updates, more buildings could qualify for a certification under the new system:
There are some caveats with WELL v2, however. For instance, a building has to meet all required 23 preconditions before qualifying a certification. If one precondition is not satisfied, the building may not proceed with WELL standard certification irrespective of how many points achieved. Additionally, a building must earn at least 4 points in the "Thermal Comfort" and "Air" concepts, and 2 points at minimum in the remainder of the concepts. Lastly, a building can attain a maximum of 110 points because of an additional 10 points that could be achieved for innovation and performance.
Based on most recent surveys more than 72M sqft of residential and commercial spaces have been certified around the globe to date. [71]
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR.
Indoor air quality (IAQ) is the air quality within buildings and structures. Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome, respiratory issues, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide, ozone and particulates. Source control, filtration, and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality.
Sick building syndrome (SBS) is a condition in which people develop symptoms of illness or become infected with chronic disease from the building in which they work or reside. In the scientific literature, SBS is also known as Building Related Illness (BRI) or Building Related Symptoms (BRS) or Idiopathic Environmental Intolerance (IEI).
Ventilation is the intentional introduction of outdoor air into a space. Ventilation is mainly used to control indoor air quality by diluting and displacing indoor pollutants; it can also be used to control indoor temperature, humidity, and air motion to benefit thermal comfort, satisfaction with other aspects of the indoor environment, or other objectives.
Green building refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's life-cycle: from planning to design, construction, operation, maintenance, renovation, and demolition. This requires close cooperation of the contractor, the architects, the engineers, and the client at all project stages. The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort. Green building also refers to saving resources to the maximum extent, including energy saving, land saving, water saving, material saving, etc., during the whole life cycle of the building, protecting the environment and reducing pollution, providing people with healthy, comfortable and efficient use of space, and being in harmony with nature. Buildings that live in harmony; green building technology focuses on low consumption, high efficiency, economy, environmental protection, integration and optimization.’
Building science is the science and technology-driven collection of knowledge in order to provide better indoor environmental quality (IEQ), energy-efficient built environments, and occupant comfort and satisfaction. Building physics, architectural science, and applied physics are terms used for the knowledge domain that overlaps with building science. In building science, the methods used in natural and hard sciences are widely applied, which may include controlled and quasi-experiments, randomized control, physical measurements, remote sensing, and simulations. On the other hand, methods from social and soft sciences, such as case study, interviews & focus group, observational method, surveys, and experience sampling, are also widely used in building science to understand occupant satisfaction, comfort, and experiences by acquiring qualitative data. One of the recent trends in building science is a combination of the two different methods. For instance, it is widely known that occupants' thermal sensation and comfort may vary depending on their sex, age, emotion, experiences, etc. even in the same indoor environment. Despite the advancement in data extraction and collection technology in building science, objective measurements alone can hardly represent occupants' state of mind such as comfort and preference. Therefore, researchers are trying to measure both physical contexts and understand human responses to figure out complex interrelationships.
Leadership in Energy and Environmental Design (LEED) is a green building certification program used worldwide. Developed by the non-profit U.S. Green Building Council (USGBC), it includes a set of rating systems for the design, construction, operation, and maintenance of green buildings, homes, and neighborhoods, which aims to help building owners and operators be environmentally responsible and use resources efficiently.
Displacement ventilation (DV) is a room air distribution strategy where conditioned outdoor air is supplied at a low velocity from air supply diffusers located near floor level and extracted above the occupied zone, usually at ceiling height.
The Center for the Built Environment (CBE) is a research center at the University of California, Berkeley. CBE's mission is to improve the environmental quality and energy efficiency of buildings by providing timely, unbiased information on building technologies and design techniques. CBE's work is supported by a consortium of building industry leaders, including manufacturers, building owners, contractors, architects, engineers, utilities, and government agencies. The CBE also maintains an online newsletter of the center's latest activities called Centerline.
Thermal comfort is the condition of mind that expresses subjective satisfaction with the thermal environment. The human body can be viewed as a heat engine where food is the input energy. The human body will release excess heat into the environment, so the body can continue to operate. The heat transfer is proportional to temperature difference. In cold environments, the body loses more heat to the environment and in hot environments the body does not release enough heat. Both the hot and cold scenarios lead to discomfort. Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC design engineers.
Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced each hour. Perfectly mixed air refers to a theoretical condition where supply air is instantly and uniformly mixed with the air already present in a space, so that conditions such as age of air and concentration of pollutants are spatially uniform.
The International Green Construction Code (IGCC) is a set of guidelines that aim to improve the sustainability and environmental performance of buildings during their design, construction, and operation. It was introduced by the International Code Council (ICC), a non-profit organization that provides building safety and fire prevention codes for the United States and other countries. It is a model code designed to be mandatory where it is implemented.
Joseph Lstiburek is a forensic engineer, building investigator, building science consultant, author, speaker and widely known expert on building moisture control, indoor air quality, and retro-fit of existing and historic buildings.
Underfloor air distribution (UFAD) is an air distribution strategy for providing ventilation and space conditioning in buildings as part of the design of a HVAC system. UFAD systems use an underfloor supply plenum located between the structural concrete slab and a raised floor system to supply conditioned air to supply outlets, located at or near floor level within the occupied space. Air returns from the room at ceiling level or the maximum allowable height above the occupied zone.
Sustainable refurbishment describes working on existing buildings to improve their environmental performance using sustainable methods and materials. A refurbishment or retrofit is defined as: "any work to a building over and above maintenance to change its capacity, function or performance' in other words, any intervention to adjust, reuse, or upgrade a building to suit new conditions or requirements". Refurbishment can be done to a part of a building, an entire building, or a campus. Sustainable refurbishment takes this a step further to modify the existing building to perform better in terms of its environmental impact and its occupants' environment.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration (HVAC&R) systems design and construction. ASHRAE has over 50,000 members in more than 130 countries worldwide.
Building performance simulation (BPS) is the replication of aspects of building performance using a computer-based, mathematical model created on the basis of fundamental physical principles and sound engineering practice. The objective of building performance simulation is the quantification of aspects of building performance which are relevant to the design, construction, operation and control of buildings. Building performance simulation has various sub-domains; most prominent are thermal simulation, lighting simulation, acoustical simulation and air flow simulation. Most building performance simulation is based on the use of bespoke simulation software. Building performance simulation itself is a field within the wider realm of scientific computing.
Demand controlled ventilation (DCV) is a feedback control method to maintain indoor air quality that automatically adjusts the ventilation rate provided to a space in response to changes in conditions such as occupant number or indoor pollutant concentration. The most common indoor pollutants monitored in DCV systems are carbon dioxide and humidity. This control strategy is mainly intended to reduce the energy used by heating, ventilation, and air conditioning (HVAC) systems compared to those of buildings that use open-loop controls with constant ventilation rates.
The Indoor Environmental Quality Global Alliance (IEQ-GA) was initiated in 2014 aiming to improve the actual, delivered indoor environmental quality in buildings through coordination, education, outreach and advocacy. The alliance works to supply information, guidelines and knowledge on the indoor environmental quality (IEQ) in buildings and workplaces, and to provide occupants in buildings and workplaces with an acceptable indoor environmental quality and help promote implementation in practice of knowledge from research on the field.
Dusan Licina is an engineer and researcher specializing in indoor air quality, building ventilation, and human exposure. He is a professor at EPFL and head of the Human-Oriented Built Environment Laboratory.
Evidence from systematic reviews suggests that adult populations who use active modes of transport (walking and cycling) for commuting have overall higher physical activity than car commuters, and also have decreased risk of cardiovascular disease and all-cause mortality (Hamer and Chida, 2008, Saunders et al., 2013