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Be COOL with Realistic Comfort Expectations!

Back in the old days people would dress for the weather, put another log on the fire or head to the beach to deal with extreme weather variations. Today, we adjust a thermostat and expect an immediate response and thermal gratification regardless of the capital, energy cost and GHG emissions required to support our high expectations of comfort.

In North America we have the luxury of being able to live and work in indoor environments that are conditioned to around 22.5ºC. There are significant capital and operating costs associated with financing our addiction to cooling, especially with our extreme Canadian climate. In some regions our building systems need to handle outdoor temperature variations from -40 to +40ºC.

For the next generation of buildings, maybe we need to start lowering expectations, challenging the status quo and developing smarter, more sustainable ways to achieve creature comfort and productivity. At the Mosaic Centre for Conscious Community and Commerce they are utilizing alternate systems and strategies for optimizing comfort, capital and performance as they build a unique, economically viable, highly sustainable, Living Building Challenge/LEED Platinum facility that will help set a new standard for the commercial real estate market.

Sustainable expectations for comfort is one of the norms being tested as it has a huge impact on the size of the cooling and renewable energy systems, which are really only needed for 20 days of the year when temperatures are greater than 25ºC.

What are the acceptable limits for thermal comfort that take into account comfort, productivity, capital and energy saving?

To determine the acceptable indoor temperature ranges, Dennis Cuku, President of OCE, and his staff initiated a Responsible Adults Temperature Study (RATS), utilizing his staff of 25+ engineers as the sample population. This short study was conducted during the summer months. Employees were provided with red (hot) and blue (cold) buttons on their computers and asked to indicate when they felt uncomfortable.

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The males (mostly young, fit, professional engineers) were hitting the hot button at lower-than-expected ranges, averaging at approximately 23 ºC, and were comfortable at 16/17 ºC. In talking with Andrea, who was monitoring the study, this relatively low range was attributed to the males having higher muscle mass than the females in the office and to their formal dress code—most engineers wear collared shirts and long pants. The range for the females was about the same, but at a considerably higher temperature (20-27 ºC). This increase was attributed to their flexible dress code allowing them to adjust for the weather, including shorts, skirts and open sleeves for warmer days.

The conclusion from the RATS experiment was that staff working in an office environment would not likely experience a decline in productivity or comfort level with temperature ranges of approximately 20-26ºC if the men were to adopt a more casual dress code. This has now been implemented at OCE.

To determine the cooling operating cost savings associated with allowing higher fluctuations in temperature, we referred to a study that IDI completed with Innovation Place Research Park for the 14,000 m2 121 building located in Saskatoon, Saskatchewan. Saskatoon has a climate very similar to Edmonton, where the MC4 facility will be located. The energy model showed that increasing the cooling temperature set point by 1ºC resulted in a reduction of just over 4% in annual cooling energy, or 126,000 MJ annually per ºC increase in cooling set point, or $1000/yr./ºC in cooling costs. This small change in the temperature set point would result in energy savings equivalent to the powering 4 homes, taking 1.5 cars off the road or CO2 reductions equal to planting 184 trees. This same approach applies for heating and would result in approximately the same amount of cost savings of $1000/yr./ºC.

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In regard to comfort and occupant health, higher cooling temperature set-points could have a positive effect on comfort when people are dressed in COOL summer attire. According to Occupational Health and Safety, this change is beneficial for health and there are even guidelines for maintaining a lower difference between indoor and outdoor temperatures.

This type of thinking is supported by a comprehensive study on Air Conditioning Comfort: Behavioral and Cultural Issues (Amory Lovins, Rocky Mountain Institute). In this strategic issues paper, Lovins concluded that “Existing comfort standards are more stringent than can be physiologically or economically justified” and that “Understanding why people use air conditioning is central to the challenge of providing comfort with minimal energy use and economic cost”.

RMI also concluded that comfort engineering fails to take into account acclimation, dependence and psychological differences and how people react when given control over their environment. The “comfort range” equation as defined by ASHRAE Guideline 55, is 2.5-5.5ºC and can be as large as 9ºC for the average individual. Individual variations can add +/- 7ºC to that range.

In addition to dry bulb temperature, which is used almost exclusively by designers, the Rocky Mountain Institute study suggests that there are ten degrees of freedom in achieving comfort: variations between individuals; variation over time; allowable excursions outside the comfort envelope; dynamic, rather than static, comfort conditions; metabolic rate; clothing; furniture; radiant temperature; air movement and humidity. Together, these alternatives can offer 10-30% in energy savings without violating comfort conditions.

Developing design concepts and operating strategies around these degrees of freedom, we can start to develop alternative ways to keep people comfortable using much less energy. Some considerations might be:

1.  Educating tenants on the idea of having more sustainable comfort expectations;
2.  Providing more control of the environment, such as opening windows;
3.  Using technology like convective cooling by installing Big Ass fans to move larger volumes of air quietly;
4.  Incorporating furniture that facilitates heat gain or loss;
5.  Encouraging appropriate dress for the season;
6.  Installing controls to optimize temperature set points for time of day and inside/outside temperature variations;
7.  Using night air to pre-cool the building mass and maintain temperatures with smaller cooling systems;
8.  Utilizing radiant cooling systems that have the inherent capability to keep people comfortable with higher variations in temperature.

Regulating agencies and policy makers need to get onboard with alternative strategies that make the best use of resources. From a cultural perspective, the Japanese think that it is wasteful to heat and cool rooms that are not occupied. Why not go even further and consider task cooling, like we do for lighting? Why condition the entire room? Since 2005, the Japanese Ministry of Environment has been advocating for warmer temperature settings and a relaxed dress code during the summer months. In 2007, the ministry estimated the CoolBiz campaign reduced Japan’s CO2 emissions by 1.4 million tons.

As we prepare for the commissioning phase of the Mosaic project, it is important to understand the project requirements for comfort. There are many ways to reach the optimum balance between comfort, expectation, smart design and size of the renewable energy system that will be needed to achieve net zero energy use in our extreme weather conditions.

Stay tuned for more information on “Sustainable Expectations” at Mosaic Centre, a real COOL project.

Website: Integrated Designs

Murray Guy and Dave Palibroda, Mechanical Engineers, Integrated Designs

Integrated Designs Inc. (IDI), established in 1997, is a professional consulting company that provides cost-effective project management, building commissioning, high-performance design, and energy-management services for sustainable building projects.

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