- natural and artificial lighting
- thermal comfort
- indoor air quality
- biophilia/connection to nature
Sustainable design supports comfort, health, and wellness for the people who inhabit or visit buildings. Describe strategies for optimizing daylight; indoor air quality; connections to the outdoors; and thermal, visual, and acoustical comfort for occupants and others inside and outside the building. How does the design promote the health of the occupants? Describe design elements intended to promote activity or exercise, access to healthy food choices, etc. Outline any material health strategies, including any materials selection criteria based on third-party chemicals of concern lists, such as Living Building Challenge Red List, EPA chemicals of concern, etc. Include key results on occupant comfort from occupant satisfaction surveys.
Dr. Claudia Miller, an immunologist and researcher of indoor environmental health at the University of Texas School of Medicine at San Antonio, likes to say that the goal of architecture should be to put doctors like her out of business. Although buildings are where we spend more than 90 percent of our time, strategies to promote the health and well-being of the occupants are not always a major consideration during design. One of the most effective strategies in this area is to ensure that all occupied spaces have access to light, air, and nature through an operable window. In general, no desk or workstation should be more than 25 feet from an operable window. Special attention needs to be paid to occupied spaces that have traditionally been mostly interior, such as kitchens or event spaces. The best design strategy to achieve this is to keep buildings narrow. Historically, buildings were lit only by the sun and could not be any deeper than how far daylight could penetrate the space. Electric lighting and mechanical ventilation allowed for deep floor slabs that pushed occupants further and further from the outside world, with tangible negative impacts on their health. Those without access to daylight and views have been shown to be less productive and less creative, and to take more sick days—at a significant expense to their communities and the companies for which they work. Providing daylight, fresh air, and access to natural and other biophilic design features will go a long way toward ensuring that occupants are happy, healthy, engaged, and productive.
Natural and artificial lighting
- Daylight can only penetrate to a depth of about 2.5 times the ceiling height into a building. Keeping floor plates narrow (five times ceiling height) and ceilings tall will result in a well-daylit building. A building that must be deeper could include an atrium, maintaining the same 1:5 ratio from the exterior wall to the atrium. A single-story building can be lit from above and can have a deeper floor plate.
- For deep single-story buildings, plan on top lighting with skylights, monitors, or sawtooth roofs. Skylights should be 5–8 percent of the total ceiling area, spaced two times the ceiling height away from an exterior wall and one time the ceiling height apart.
- Whenever possible, orient the long axis of a building within 15 degrees of due east-west. This will make the daylighting and shading strategy relatively straightforward and effective, and minimize excessive solar heat gain and glare that is more difficult to control when the sun is lower in the sky.
- Daylight and view windows have different purposes and require different geometry. View windows exist between 3 and 7 feet above the floor; while daylight windows generally exist above 7 feet.
- Daylight needs opaque light smooth surfaces on which to land, reflect, and illuminate. Too much interior glass or dark surfaces will make a space feel dark, regardless of how much daylight comes in.
- Glare is not a problem of too much light, but rather a high contrast between light and dark surfaces. A bright but unevenly lit space will appear dark, and occupants will turn on electric lights. The best strategy is to daylight from multiple sources and directions.
- Daylighting works as an energy-saving strategy only if the lights are off. To ensure this, all buildings should include photo-sensors that control continuous dimmers. Lighting should be wired parallel to the exterior wall. Each row or each light should be individually controlled with a light sensor.
- Democratize daylight by moving shared spaces to the perimeter, where the daylight can benefit the most people.
- Task lights allow overall lighting levels to be lower, which saves energy. Task lighting also gives people added control over their environment, which has been shown to increase satisfaction.
- Set target metrics for lighting-power density and foot-candle levels for each space. Best practice is to design toward an established target appropriate to the anticipated tasks. Electric lighting should be designed to supplement daylighting, as opposed to providing all necessary light.
- Focus on thermal symmetry to ensure that conditions are similar throughout the space and through an individual body. Strategies to achieve this include optimized insulation; low U-factor window frames; spacing windows and fans evenly; shading south, east, and west glazing; and avoiding thermal bridges. Pay special attention to the location of air registers. Nevertheless, consider opportunities to break these rules for the purpose of thermal delight.
- A building of substantial thermal mass is generally more comfortable than a lightweight building because dense materials even out potential thermal asymmetry. This strategy is especially effective in regions with large diurnal shifts in temperature.
- Radiant systems, for both heating and cooling, create more comfortable spaces than forced air systems. Physiologically, humans are more efficient at regulating body temperature through radiation than convection. Radiant systems also eliminate drafts and can improve air quality (with a lower energy profile than forced air).
- Giving individual occupants the ability to control their immediate environment will result in greater occupant satisfaction. Occupants report being more comfortable when they have controls, whether or not they actually use them. Humans also report greater thermal comfort in spaces with operable windows.
- Address all six factors of thermal comfort: air temperature, humidity, mean radiant environment, metabolic rate, air movement, and clothing.
Indoor air quality
- Contaminants tracked into buildings on occupants’ shoes are a major source of indoor air pollution; intercepting this matter is the first strategy for indoor air quality. For commercial buildings, particle interception is usually a 10-foot walk-off mat or entrance grille oriented in the direction of travel. For residential projects, this can be a smooth, easy-to-clean surface or a mat at the primary entrance. Encouraging people to remove their shoes near entrance thresholds is another good particle interception strategy.
- Combustion from gas ranges, boilers, fireplaces, or water heaters is a major contributor of indoor air pollution, even with the use of fume hoods and exhaust vents. Indoor combustion within the conditioned spaces should be eliminated whenever possible. Consider using all-electric appliances and equipment (induction ranges, etc.) to capitalize on future connections to solar PV battery backup and to match carbon-neutral utility grids in the next 20 to 40 years.
- Material off-gassing is another source of indoor air pollution. Choose "no VOC" (Volatile Organic Compound) over "low VOC" for paints, sealers, and adhesives. Pay special attention to finishes, furniture, fabrics, plastics, composite materials, and anything else that might off-gas. Avoid flame retardants. A good standard for emissions criteria to follow is to check if the emitting material or composite product meets CDPH (California Department of Public Health) criteria.
- Chemicals such as cleaning products should be stored in rooms with negative pressure and single-pass ventilation. Laser printers and copiers, which emit VOCs and fine particulate matter, should also be segregated.
- All buildings in humid climates (Gulf Coast and Eastern Seaboard) should have standalone dehumidification systems to help prevent the growth of mold and mildew.
- Choose a high-quality air filtration system to eliminate airborne contaminants and provide dedicated outdoor air to keep indoor carbon dioxide to a minimum. It is important that the ventilation system is not connected to the primary thermal conditioning system, so that fresh clean air can still be delivered to a space when heating or cooling is not needed. Incoming ventilation air can be tempered by mixing with recirculated conditioned air, or air exhausted through an Energy Recovery Ventilator (ERV).
- Plan on measuring the air quality post-occupancy to verify the strategies listed above.
- Good health is a great indicator of happiness. Strategies that promote human health, such as providing nutritious food and opportunities for exercise, will promote happiness as well.
- We tend to get bored when presented with the same thing repeatedly. The first apple is great, the second less so, the third fairly average, and the fourth might even decrease happiness. This is called the law of diminishing returns. The saying “variety is the spice of life” is true in that we require new and ever-changing experiences to remain interested. Variety is best experienced over time rather than all at once. For an abstract example, one room that can transform and create a different experience each month is better than 12 different rooms that remain static.
- People are happiest when they perceive a sense of control. This can be as simple as being able to open a window or adjust a thermostat. Think about flexible spaces that can be individually manipulated and provide options to experiences different environments. Generally, more choices—even if additional choices are unlikely to be chosen—will increase perceived control.
- Self-actualization is the realization and fulfillment of an individual's feeling of self-purpose. This takes place in the form of intense concentration and creativity, and is often described by athletes, artists, and musicians as being 100 percent engaged in a task for an extended period of time. Achieving self-actualization requires an environment free of nuisances and distractions (glare, disrupting noises, thermal discomfort, poor air quality, etc.)
- People often describe their best experiences as “authentic.” Creating authenticity by referencing culturally meaningful ideas will make people more likely to value an experience. This also helps root a project in the community, celebrating a unique sense of place.
- An equitable environment makes people feel that they are respected and that their thoughts and opinions matter. These environments are more likely to encourage trust and camaraderie and will encourage people to look out for each other. An inequitable environment might make people feel they need to compete for resources. An example of an equitable environment is one where organizational hierarchy is not manifested in the architecture.
Biophilia/connection to nature
- Incorporating biophilic design into projects has a direct and measurable impact on occupant health and well-being. To be successful, biophilic design should create an authentic connection to nature.
- Set maximum background decibel targets. Early on set space-by-space targets for maximum background noise. Identify which spaces will be loud and space them accordingly. Identify environmental noise such as roads or machinery, and develop strategies to mitigate their impact.
- Set Sound Transmission Class (STC) targets. Determine target STC ratings between spaces, and develop wall assemblies to achieve the target. Remember that acoustical walls with high STC ratings are thicker than normal partitions.
- Set Noise Reduction Coefficient (NRC) targets. The NRC rating of the finish materials in a space determines both the amount of noise in a space and the reverberation time. All regularly occupied spaces should be treated with sound-absorbing finishes. A rule of thumb is to apply acoustical materials with an NRC of 0.7 or above to an area equal to 80 percent of the ceiling. This material can be placed on either the ceiling or walls.
- Limit glazing. Glazing performs poorly both in terms of STC and NRC and highly glazed spaces are often noisy. Thick insulated glass can have an STC rating as high as 40, about the same performance as a stud wall with batt insulation. Acoustical glass can be very expensive.
- A strong correlation exists between the healthiness of food and the energy required to prepare it. For example, french fries are both less healthy to eat and more energy intensive to prepare than a fresh salad. Keep this in mind when designing kitchens in low-energy buildings. The menu will have a big impact on both building performance and occupant health.
- Look for opportunities to produce food on-site. This could be with a vegetable or herb garden, fruit trees, chickens, bees, livestock, or wild edibles.
- As much as possible, advocate for high-performance food (simple foods) to be served in high-performance buildings. Focus on options that are healthy, plant-based, local, and generally low in embodied energy. At the very least, there should be healthy choices available; this is especially important in schools.
- Advertising for highly processed foods such as soda, candy, or fast food should be avoided.
- Establishments that serve food should have a designated place, either a board or screen, where food nutritional information can be displayed.
- Design circulation around stairs rather than elevators to promote physical activity. The logical flow of the building should be based on human-powered vertical transportation. Make the stairs beautiful. Simultaneously, provide great vertical experiences for those with wheelchairs, strollers, or bicycles. Move the elevators to a location that is less obvious or out of the way.
- Include equipment or amenities for structured exercise, such as pull-up bars or aerobic stretching, and/or flexible spaces for group exercise.
- Provide a variety of options for work stations, including adjustable-height sit/stand desks.