Fenestration Forum: January-February 2011
By Brian Burton
Breaking the model energy code
By Brian Burton
Now that the updated model energy code (NECB 2011) has been formally
released, several apparent limitations regarding the actual application
of the code have been raised by various stakeholders in the industry.
Now that the updated model energy code (NECB 2011) has been formally released, several apparent limitations regarding the actual application of the code have been raised by various stakeholders in the industry. If you study the code documents it’s quite obvious that this is a very complex undertaking.
In large part, this is a result of the wide range of climactic conditions across the country as well as the large number of different housing and building types. In addition, construction technology in general and fenestration elements in particular are becoming more and more complex. It shouldn’t come as a surprise that the code documents appear to require some “fine-tuning.”
Prior to the release of the model energy code, most of the attention was focused on the costs it might impose on the industry and the limitations it could place on designers. There is also an ongoing debate about using the “simple payback method” as opposed to “total life cycle cost analysis” to calculate life-cycle costing.
When it came to the new model energy code, the intended mandate was to improve energy efficiency in buildings by 25 per cent. Part of the development of this standard involved attempting to match the existing ASHRAE Standard 90.1, which describes the minimum required prescriptive R-values for roof and wall insulation levels for various climate zones in the United States.
Normally energy codes provide several different means for the designer to comply with the code. The first is termed “prescriptive,” which basically defines minimum energy requirements for all components. The second involves allowing “trade-offs” between the various building components in their energy use – as long as the total energy savings do not differ significantly from those that would have been achieved by a prescriptive path.
Several technical challenges were identified when industry experts applied the formula to some building designs and found that using the new code presented difficulties when attempting to achieve the energy efficiency targets for some specific building types. There were also other limitations pointed out that occur when attempting to apply the “fenestration to wall ratio” in colder climates zones using standard building practices. As a result, recommendations have been made to the Executive of the Canadian Commission on Building and Fire Codes regarding certain alterations that could be applied that could improve the new code.
Feedback received from the industry suggests that effectively applying the new code will be a challenge for certain types of buildings; namely, semi-heated warehouses, hospitals, hotels and strip malls. In simple terms, this means it will be very difficult to achieve a 25 per cent improvement in energy efficiency for these types of buildings.
Recommendations about how to make the necessary adjustments in the code have been put forward and are being considered by the various government standing committees that are involved, including the Executive of the Canadian Commission on Building and Fire Codes.
I suspect these modifications can be made without too much difficulty and, in my view, Canada has once again demonstrated its expertise in the field of building science and construction.
Some of the key elements in the code regarding general improvements in energy efficiency are as follows:
Air leakage: Air leakage has a significant impact on the energy performance of buildings. As a result, stricter air barrier requirements are to be implemented and testing of air barrier assemblies will be required.
Assembly construction: There will be no exemption within the prescriptive requirements for any assembly construction. As a result, some experts are suggesting that certain industry sectors will have more difficulty in meeting the prescribed performance levels for building envelope assemblies than others.
Baseline construction: Technical changes to any of the four National Model Codes contain supporting information that includes the cost implications of the proposed change.
Control devices for lighting: Lighting of unoccupied interior spaces is considered wasteful.To remedy this problem, the new code requires installation of automatic lighting controls for most applications.
Costing: Traditionally, model codes for buildings, plumbing and fire protection are focused on occupant health and safety and do not usually take costing into account. Some construction professionals feel that this approach is not appropriate in developing energy codes and argue that costing should be carefully considered and evaluated.
Fenestration to wall ratio: The prescriptive building envelope requirements in the new code will set a maximum fenestration to wall ratio of 0.30.
Heat recovery: Heat recovery equipment produces significant energy savings by preventing the loss of waste heat and the document has provisions requiring the installation of heat recovery equipment for most occupancy types.
HVAC and service water heating equipment: Minimum standards for energy efficiency of HVAC and water heating equipment have been established with certain provisions based on building type.
Advances in construction materials and methods: Generally, most stakeholders recognize that advances in construction materials and methods have made it possible to achieve the goal of improving energy efficiency by 25 per cent, regardless of how the building is being used and regardless of the occupancy type.
Brian Burton is a Business Development Consultant for Kleinfeldt Consultants. He can be reached at firstname.lastname@example.org.