Maximize your Builder’s bottom line through Energy Efficient design (Part II)
In Part I we discussed a new set of design rules that address both environmental sustainability and the shift in homebuyers’ expectations, how they relate to a softening market and improving your builder’s construction quality and bottom line. We also indicated that certain design rules should be “non-negotiable”; especially ones that affect indoor air quality, home comfort, energy efficient design (lower operating costs), and an ongoing design review process. The philosophical change for the designer / architect is that he must be fully engaged in managing both the builder’s and the homebuyer’s expectations. The homebuyer’s purchasing experience, from the point of sale to possession must be engineered with the same attention to detail as the architect puts into the house design. The design details must help facilitate the positive purchasing experience for the homebuyer. Sound complicated? Here is a formula that has worked.
Understand the need for a tight building envelope and how to achieve it. Most builders in Southern Ontario are using a combination header wrap and poly (vapour barrier) to achieve a continuous air barrier. There are many design details we use that make achieving a tight building envelope virtually impossible. Some of the worst offenders are:
Proper installation of header wrap. This is a critical part of the building envelope and must be detailed properly.
Room over garage; a drop ceiling with a heated cavity. The misconception is that the bedroom above has a cold floor because of the unheated garage below. In reality, it is drafts caused by air leakage that results in the comfort complaints. The solution: spec spray-foam the joist spaces and surrounding structures such as rim joists, steel beams and penetrations into the living areas. This will increase the R-value and stop the drafts.
Room over porches and cantilevers; because there is no poly between the insulation and the living (conditioned) space, there is usually no air barrier. The solution: provide details on how to install house wrap on the cold side of the cantilever or spec spray- foam for the entire space.
Back-framing; is usually installed before poly therefore the poly, cannot be installed as a continuous air barrier. Framers are great at framing but if you want them to insulate, they need proper training. The solution: advise builders to back-frame after poly or provide details for the framers on how to correctly install the poly.
Designers need to have discussions with their builders about these problem areas, how they impact customer complaints and service. Builders require simple and proven sustainable design alternatives. Familiarize yourself with ENERGY STAR, LEED-H and GreenHouseä specifications, as many of Ontario’s top builders have adopted these building standards. A recent J.D. Power survey commissioned by EnerQuality indicated that 84% of new homebuyers see energy efficiency as very important on their next purchase decision.
In the next issues of Builder/Architect Magazine, Part III will explain how you can apply some simple value-engineering principles, which will improve the builder’s bottom line and result in a more energy efficient and better-built house. There will also be some suggestions on what both Builders and Trades are coming to expect from Construction drawings to help them deliver a value-added product.
Al Schmidt is a building and energy consultant and trainer for EnerQuality Corp., a service provider for the R-2000 program, ENERGY STARâ for New Homes, Building Canada, LEED-H, GreenHouse Certified Construction and EnerGuide Rating System. EnerQuality has been in the business of promoting “best building” practices in Ontario since 1998.