ASHRAE Journal - June 2011 - 58

Building Codes: Where Are We Headed?
We have operated for years with prescriptive standards as the basis of our building codes, and they have served us well. However, as we look for greater energy efficiency, it is apparent that it could only be achieved by addressing building operations as a whole, rather than as a series of parts. In addition, our current buildings codes only address design and construction issues, and their impact typically ends with a certificate of occupancy. Performance standards and their resulting code applications can allow a more holistic and sophisticated systems approach to building design and construction, providing that they address objective, function and methods in their analysis. They can allow analysis of building orientation, and its impact on solar heat loads and on the use of daylighting. More importantly, performance standards can allow closer analysis of the interaction of all buildings systems, especially if plug and process loads are included. However, even this approach comes up short as we seek out higher and higher performance, because it fails to account for the impact of the building owners and occupants. Building occupants have control over three critical building functions: plug and process loads, lighting and thermal comfort. Collectively, these can account for 30% to 60% of the total building load. The occupants’ actions, in turning off computers and task lights when not in use, can have a major impact. Much of that may require changing behavior, mindsets and culture. Thermal comfort is a classic example. ASHRAE Standard 55 clearly defines a range of temperature, humidity and air movement acceptable to 80% of building occupants. Simply put, most occupants are comfortable in a range of temperatures between 68°F and 78°F (20°C and 26°C) (dependent upon such issues as clothing air movement and humidity) yet many building occupants insist on setting space temperatures at (say) 72°F (22°C) and expecting control at ±1°F (±0.5°C). In Europe, for example, the comfort temperature band is treated as a dead zone, requiring neither heating nor cooling in that range. This can save significant amounts of energy; however, some will regard this as a trade-off for comfort. Gaining compliance could be a major shift toward controlling consumption. How do we change behavior? First, by raising public awareness of energy and the environment and, second, by developing a culture of sustainability. It will require a different approach in buildings standards and code application that takes us beyond building design and construction and into actual operations. Outcome-based codes and standards can regulate actual building energy use in real life operation, but would require a wholesale change in the way we currently do business. It could impact the way that buildings are designed, constructed, operated and maintained, including periodic auditing and performance verification. Achieving that will not be easy and will require agreement on common performance metrics, establishment of a normalizing formula for weather, occupancy use and other factors.
June 2011

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ASHRAE Journal - June 2011

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