Solar control and productivity

by Katie Daniel | October 13, 2017 4:09 pm

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By Terry Coffey
Solar control solutions are important in helping increase worker productivity. To understand how, one must understand what makes a productive building, and why productivity should be a consideration in design.

Shading systems have traditionally been presented as a way to achieve energy cost savings by using natural light and solar heat gain control to lower utility bills and reduce the size of HVAC and lighting systems. However, by far the biggest amount of money spent annually on a commercial operation is not energy-related, but people-related. Wages and other workforce costs comprise the biggest chunk of operating expense; in this area, shading solutions can also have an impact.

According to the “Productive” section of the National Institute of Building Sciences’ (NIBS’) Whole Building Design Guide (WBDG), typical total life cycle costs of private-sector buildings are:

• $2150/m² ($200/sf) per year for salaries;
• $215/m² ($20/sf) per year for amortized bricks/mortar cost; and
• $21.50/m² ($2/sf) per year for energy.

Based on those numbers, even a very small improvement in productivity can have a huge impact.

WBDG puts forward five basic principles that are part of “productive building designs.” They are:

• promote health and well-being;
• design for the changing workplace;
• integrate technological tools;
• ensure reliable systems and spaces; and
• promote comfortable environments.

(For more on these principles, visit the Whole Building Design Guide by the National Institute of Building Sciences [NIBS] at wbdg.org/design/productive.php#mjr[2].)

In addition to those five principles, the WBDG has this to say:

Buildings can be more effective, exciting places to work, learn, and live by encouraging adaptability, improving comfort, supporting sense of community, and by providing connections to the natural environment, natural light, and view.

Based on these factors, window shades and other solar control solutions can have an impact on improved productivity as part of an overall daylighting strategy.

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The case for natural light
People need natural light to create enzymes and proteins for a healthy life. Without enough natural light, the body’s circadian system can no longer properly regulate things like sleep, alertness, and concentration. According to an article from 2000 in the Journal of Occupational Rehabilitation, lack of sleep makes it more difficult to make decisions (This information comes from S.J. Linton and I. Bryngelsson’s 2000 article, “Insomnia and Its Relationship to Work and Health in a Working-age Population,” in the Journal of Occupational Rehabilitation 10[2], 169-183.), and a 1995 Journal of General Internal Medicine report links insomnia to poor job performance. (The report, “Sleep Problems and Their Correlates in a Working Population,” was written by authors M. Kuppermann, D.P. Lubeck, P.D. Mazonson, D.L. Patrick, A.L. Stewart, D.P. Buesching, and S.K. Fifer for the Journal of General Internal Medicine 10, pp. 25–32.) Further, a 2009 CÉGEP  Champlain-St. Lawrence study in in Sainte-Foy, Qué., found insomnia costs the Canadian economy $20 billion per year. (For more on the study, read Andre Picard’s “Insomnia Costing Economy $20 Billion a Year,” published in The Globe and Mail on January 1, 2009. Visit www.theglobeandmail.com/news/national/insomnia-costing-economy-20-billion-a-year/article1068078[4].)

The key is natural light, which cannot be replaced just by having an effective electric lighting system. Another 1994 study showed there was a statistically significant improvement in job performance in offices with windows. (The study in question was A. Hedge’s “Reactions of Computer Users to Three Different Lighting Systems in Windowed and Windowless Offices,” in Work and Display Units, 94, B54-B56.) The Center for Building Performance and Diagnostics at Pennsylvania’s Carnegie Mellon University looked at the impact of daylighting on productivity and recorded 40 per cent gains when daylighting was introduced into offices. (This is so according to “High-performance Buildings Enhance Workers Effectiveness and Productivity Through Improved Health, Communication, and Comfort” by the Center for Building Performance and Diagnostics.)

Evidence also suggests workers make fewer mistakes in environments with plenty of natural light. One 2003 study of pharmacists found a 3.5 to 2.6 per cent decrease in dispensing errors occurred when light levels were increased from 450 lux (42 fc) to 1500 lux (139 fc). (The study was P. Boyce, C. Hunter, and O. Howlett’s “The Benefits of Daylight Through Windows,” provided from Troy [NY]: Lighting Research Center.) Thus, natural light—and the means of getting it into a building—should be an essential part of designing a building for maximum productivity.

There is more to it than just the light itself, however. Access to window views to the outside also gives workers a connection to nature, which has been found to have an impact on mood, satisfaction, and performance. Another 2003 study showed the mood of daytime workers was significantly better than nighttime workers in the same office with windows. (This information is from U. Dasgupta’s “The Impact of Windows on Mood and the Performance of Judgmental Tasks, M.S. in Lighting thesis,” from Rensselaer Polytechnic Institute.)

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The case for solar control
There can be some negatives when more windows are incorporated into building design. Glare, solar heat gain, and direct sun on workers’ eyes or workspaces can make it harder to perform basic work functions and can actually lower productivity.

WBDG states:

The science of daylighting design is not just how to provide enough daylight to an occupied space, but how to do so without any undesirable side effects. Solar control solutions, including both exterior and interior shading systems, are thus an important part of designing a productive building.

(For more, visit the website wbdg.org/resources/daylighting.php?r=productive[6].)

In 2006, Heifer International opened its new headquarters in Little Rock, Ark. The building was designed with sustainability and natural light in mind. It included energy-efficient plate-glass windows for passive solar heat and indirect light, as well as a curved shape to capture the maximum amount of sunlight. These and other sustainable construction practices helped the building earn Platinum under U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) program. However, when the facility opened, a glaring problem emerged: workers could not use their computer stations on the south side of the building due to the sun load coming through the extra-large windows. While fixed sun shades were in place to help with passive solar control and glare, workers were getting additional glare from the water surrounding part of the building. The problem was resolved by adding interior window shades, with a five per cent openness factor to still allow views through to the outside.

Thermal comfort
In addition to glare, solar heat gain can also be a problem. Thermal comfort contributes to job performance and productivity, and WBDG recommends a holistic design approach to deal with this, including use of solar-shading products. (More information is available at wbdg.org/design/provide_comfort.php[7].) Resolving this issue gives an exterior system the advantage, because it prevents a large part of the sun’s energy from reaching the glazing and entering the building.

Energy from the sun is short-wave (i.e. visible, ultraviolet [UV] light) and carries little heat. Reflected solar energy is also not an issue—it remains short-wave, and does not cause any heat gain. Heat is only produced when solar energy is absorbed by a surface (e.g. carpeting, furniture, clothing, or skin) and radiated as long-wave infrared (IR) energy. Transmitted energy (i.e. that absorbed by surfaces in the building and radiated as heat) is then mostly trapped inside the building, particularly if low-emissivity (low-e) glazing is used. (For more information, visit wbdg.org/resources/suncontrol.php?r=provide_comfort[8].) If the solar energy does not get into the building, however, it does not have to be dealt with.

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Incorporating solar control at Manitoba Hydro Place
As every building type, design, and location is different, there is no ‘one size fits all’ solar control solution. There are many types of systems—from venetian blinds to fixed louvres to fabric/roller products—that can be used, depending on the situation. Whichever type of solution is required, however, it is important to have a system that can react according to the prevailing conditions while retaining local control so individual comfort is taken into account. (See Richard Wilson’s 2014 article for The Construction Specifier, “10 Key Questions About Solar Shading,” at www.constructionspecifier.com/10-key-questions-about-exterior-shading[10].)

Manitoba Hydro Place is a 21-storey office building in Winnipeg, designed by KPMB Architects. Since it was completed in 2009 (and certified to LEED Platinum in 2012), the building has received significant attention for its green features and energy efficiency. The building design incorporates features such as a double façade with integral 100-mm (4-in.) venetian blinds and operable windows, a solar chimney, ground-source heat pumps, radiant ceilings, and six-storey atria that act as thermal buffers.

According to an article in High Performance Buildings magazine, the building’s annual site energy use is 92.3 kWh/m² (29.3 kBtu/sf). This compares with an annual average energy usage of 325 kWh/m² for a typical high-rise office building in Winnipeg. The article notes the building uses 52 per cent of the energy of a building complying with American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 90.1-2007, Energy Standard for Buildings Except Low-rise Residential Buildings. In addition to energy performance, one of the five key design requirements was to create a supportive, healthy workplace environment for the employees of Manitoba Hydro. (For more information, see “Manitoba Hydro Place–A Climate Responsive Design Model” at manitobahydroplace.com[11].)

A dedicated website about the building, prepared by KPMB, describes the double façade:

Full height glazing throughout the workspaces allows for unobstructed views, while a fully automated louvre shading system within the double-façade stops unwanted solar gain when appropriate. The angle of the 100-mm deep louvre shades can be adjusted as required to suit sun location and angle. When light levels are low enough, the louvre system can be fully retracted and stacked tight against the ceiling in the step of the slab. Computer models of the surrounding tall buildings, in combination with active real-time data from the building’s weather station, optimize the blade angle and determine how each louvre shade should be deployed. The top portion of the shade assembly is set at a different angle from the lower blades to act as a series of small light shelves, bouncing light onto the white ceiling, while the lower portion is closed. When fully deployed, the aluminum louvre blades feature a finely perforated surface, stopping solar glare, but still allowing views to the outside.

An oft-cited concern about using automated systems is reliability and maintenance. A recent article in Green Building Advisor considered some of the issues associated with the operation of such a complex building. According to one of the building energy management engineers at Manitoba Hydro, the venetian blinds in the double façade have been very reliable. He says, “I think the key message is that our building has three building operators fully responsible for all 65,032 m² (700,000 sf), so the operations and maintenance costs are lower than what we’ve seen with our traditional office buildings.”

The venetian blinds are only one aspect of the environmental design of the building, but they provide a contribution to the energy performance, assist in the management of natural daylight, and maintain outside views. Further, as demonstrated above, this will contribute to improved productivity throughout the life of the building.

 

Terry Coffey is an external communications specialist for solar control solutions provider Draper Inc. He has been with the company since 1999. Coffey can be reached via e-mail at tcoffey@draperinc.com[12].

Source URL: https://www.constructioncanada.net/solar-control-productivity/

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