|September 08, 2009|
Can you be Comfortable in a Green Building?
|Building performance and its evaluation have earned increased attention in recent years, particularly relating to green buildings. Much of the emphasis has been on optimizing energy and resource efficiency. Despite the recent media buzz around the actual performance of LEED-certified buildings, surprisingly little attention is being paid to the human resource within buildings. |
Green buildings, according to the Canada Green Building Council (CaGBC), are buildings designed to balance environmental responsibility while providing a comfortable, healthy and productive environment within economic means.
In contrast to their conventional counterparts, green buildings often rely on natural air conditioning to meet the comfort needs of end-users. A combination of ’passive’ design strategies [pdf] may be used to provide indoor comfort conditions, including the use of mass to retain and radiate heat, passive solar heating, passive cooling, natural ventilation and daylighting.
The resulting indoor environmental quality may be far superior from the perspective of building occupants. Indoor air quality in green buildings is enhanced by supplying high levels of outside air and using low pollutant materials; indoor conditions are often more closely linked to outside conditions; the use of natural light supports ’biophilic instincts’, along with views to the outdoors, and direct contact with nature; and occupants may have a greater amount of personal control over their workspace through opening and closing windows, blinds, switches and other manual controls.
Improved indoor environmental quality can benefit building owners, not only in terms of improvements in occupant comfort and health but also productivity. Seminal work [pdf] by the Rocky Mountain Institute links efficient lighting, heating, and cooling to measurably increased worker productivity, decreased absenteeism and improved quality of work in eight case-study buildings.
A web-based tool, e-Bids, now available from the Centre for Building Performance and Diagnostics at Carnegie Mellon University, documents the power of arguments to date for various green building design strategies in terms of energy savings, health cost savings, productivity gains and return on investment. The take home message from these landmark studies is that occupant comfort, health and productivity can payoff just as much as energy and resource conservation over the lifetime of a building.
Do all green buildings lead to improvements in user experience?
Evidence from recent post-occupancy evaluation studies suggests not. A study [pdf] by the Centre for the Built Environment, U.C. Berkeley, comparing satisfaction between green and non-green (or conventional) buildings, found that occupants in the green buildings were more satisfied on average with the building overall; they were also more satisfied with air quality and thermal comfort.
However, they were, on average, less satisfied with lighting and acoustics as compared to conventional buildings. In similar work by the Usable Buildings Trust, U.K., green buildings as a group scored better on indoor environmental quality factors, while a few of the lowest scoring buildings were also green, especially in terms of glare and acoustics.
In contrast, a study by the Pacific Northwest National Lab of General Service Administration buildings found higher satisfaction in green buildings across the board, including for lighting and acoustics, compared to the non-green buildings dataset.
The findings are therefore mixed. Although green buildings have the potential to enhance indoor environmental quality, they can fall short in the following commonly reported areas:
Acoustics Poor acoustics is one of the most problematic features of green buildings. The combination of design strategies, such as the use of open atriums and high ceilings to allow natural light into unlit spaces, and the use of low material finishes to improve air quality and reduce resource use, can have negative consequences for indoor acoustics. Because noise will travel wherever air does, typical complaints in spaces with these two common design strategies include noise pollution, echoing and amplification through a building, frequent distraction, and trouble focusing on work due to noise.
Lighting and glare Many green buildings use daylighting strategies to improve visual comfort while reducing electrical lighting load. However, unless combined with appropriate shading strategies, daylighting can lead to glare on computer screens from the sun and sky, impacting occupants’ comfort and productivity at work. This is usually reduced by shutting blinds and turning on lights, which can increase building energy consumption.
Summer thermal comfort Naturally-ventilated green buildings tend to be hotter in the summer than mechanically cooled buildings in the same climate. This aspect is less frequently complained about than others, possibly due to the fact that occupants can adapt to a wider range of conditions in naturally-ventilated buildings than in mechanically-ventilated buildings, as well as recent evidence supporting air movement as an equally important means to control thermal comfort as air temperature.
Ineffective controls Occupants who experience discomfort, but find they can’t do anything to change their situation, become distracted and frustrated. When building controls or building operators don’t respond efficiently or effectively enough to requests for changes, occupants may tamper with building systems and control points, or bring in fans, heaters, or lamps to their workspace, and both of these outcomes will affect building efficiency and utility.
How do we ensure green-designed buildings are also comfortable in use? A recent study by researchers at the University of British Columbia suggests that ’feedback’ (generating knowledge about a building to guide future decision-making and behaviour) may be a key part of the solution.
Many occupants have pre-existing expectations about green buildings and their performance. When those expectations are coupled with an understanding of the building design and systems, occupants can be more comfortable overall and forgiving if things don’t turn out as they would like.
Research shows over and over that occupants of green buildings do want to learn about their how their building works, but there is often a gap between the desire to learn and the quality of information provided.
Workers surveyed for the UBC study of a LEED®-Silver building commented: "It is a great shame that there has been no explanation to the users of how the building has been designed to operate, and provide us with guidelines as to how we should manage the lights, the heating system, and other environmental performance features".
The research suggests that the best way for occupants to gain familiarity with their building is through involvement in building design and occupancy phases (e.g. design charettes, building tours, building completion), and ensuring that quality feedback is provided during building use in terms of usable, effective and responsive controls.
The next article in this series will take a closer look at using feedback to improve green building performance, and the relationship between smart buildings and smart occupants.
Zosia Brown and Sylvia Coleman, are PhD students at the Institute for Resources Environment and Sustainability, UBC. This article is part of a special GLOBE-Net Series "Building Tomorrow."
The Institute for Resources, Environment and Sustainability (IRES) is both an interdisciplinary research institute and a major interdisciplinary graduate education program at the University of British Columbia. It is the mission of IRES to work to foster sustainable futures through integrated research and learning about the linkages among human and natural systems, to support decision making for local to global scales.