July 13, 2018
A few years ago 2 other building science educators and I, helped facilitate a series of builder design charrettes. Each time about 40 builders were given 3 days of comprehensive building science training that included on-site investigations, testing, case studies, building material presentations and evaluations. The builders, working in groups of 5 were then asked to apply what they had learned and experienced to a single-family design project. They were asked to "build a house that you would feel good about building for your favoured clientele".
Upon completion, while we evaluated the energy performance improvements they had made using HERs software, the builders were asked to cost out the incremental costs of their chosen advancements. It was a surprise, even to us, that in each group in each of the seven sessions, the annual energy savings of their chosen advancements provided a positive return on investment against the incremental estimated construction costs applied to the mortgage of the house. That is, the total annual cost of ownership for the improved design was always projected lower than the costs for the standard, reference design.
Then came an intriguing exercise. Each team was asked to evaluate or score their project against a few of the most common green building programs such as LEED for Homes and the US National Green Building Standard. In each case, the eight teams in each of the seven sessions found that the design elements they had chosen helped them achieve at least the middle range, Silver or Gold, in the program they chose. The builders, initially skeptical about the need for green, learned that most of the common sense decisions they felt compelled to make to ensure a high performance home were simultaneously recognized as being green. Looking at this more closely, most green programs, in addition to energy conservation, reward decisions that improve indoor air quality, water conservation, material conservation and sustainability and overall building durability. Following are some examples of elements I learned from these builder charrettes and many of them we were able to incorporate in the LEED Platinum cottage we completed recently.
Start with an obvious win-win; advanced framing. Lower construction costs, improved energy performance and points within green building programs. Certainly it requires design considerations, process changes and training of framers and other contractors, however, with the move in codes to "effective R-value" recognition, advanced framing is something that should be on all builders' agenda for 2018. In the cottage construction, the framers admitted we went a little overboard in striving for minimized wood use. They ended up adding back a few elements around windows and doors for trim and backing, but overall the walls were lighter and quicker to build.
Next, the most important to me as I travel and see the impacts of improper water management details, is the recognition in LEED and other programs for durability measures. Specifically, fully drainable, dryable building enclosures that includes shingled, lapped house wrap details, window flashing, sill pan flashing, head flashings and drip caps over all windows and doors. In my case, I am a big fan of a systems approach such as provided by the DuPont Tyvek weatherization system. The builders in the charrettes chose it after having seen in the site walks the potential risks associated with ever more complicated building enclosure details combined with the lowered drying potential of buildings due to increased insulation levels. I like the warranty protection offered by one of the world's leading building materials manufacturer.
Another really simple, cost effective cost effective decision is to choose materials that have lower off-gassing potential to enhance air quality. One great example is the availability of high quality sealants and adhesives such as the relatively new LePage Quad Max window sealant that has less than 3% volatile organic compound content and yet can be applied down to -18 C and in any moisture condition and provide better flexibility than any other currently available. There are similar low cost opportunities in paints, sealers and building materials. Its time to re-evaluate your material choices and add indoor air quality parameters to your decision matrix.
We are on a great path to minimize precious energy resources over the next 10-12 years. In that same time frame there will be increased pressure to optimize water use. The easy start to that are the reliable and effective ultra low flow shower heads and dual flush toilets. I really like the experience of the Delta H2O Kinetic shower heads at water flow rates of under 2 gallons per minute. Then in the cottage we installed a 4,000 liter rain water cistern to flush toilets and water the grass. While the cistern itself was less than a $1000, the pump and controls needed to satisfy the municipal water works needs for pressure control and backflow potential was many thousands more. A decision I wouldn't recommend for mainstream housing. In my opinion the newly available packaged grey water systems will be a much more cost effective way to minimize the single largest use of water in most homes water by using waste water to flush the toilets.
These were but a few of the 30 or so decisions we considered in designing and building the cottage. In that effort we used the same philosophy as the builders in the design charrettes used. Rather than "chasing" green points, stars, bars or colours, we used the helpful, well researched resources and checklists available from programs such as LEED for Homes to help make informed, cost effective decisions. Those resources combined with now over 40 years of the building science research into programs such as the R-2000 and ENERGY STAR program can help you build healthier, safer, more comfortable, more durable and indeed more cost effective homes for your buyers. Then go ahead and score your homes against the green building program of your choice and you will find they will reward you with useful recognition of your decisions.
Written by Gord Cooke.
This article originally appeared in Better Builder Issue 25 - Spring 2018