HIGH PERFORMANCE BUILDING
I've had the opportunity to project manage the construction of a number of high-performance building projects. The definition of high-performance building is likely to be different for different builders, home owners, organizations and agencies, so a universal definition is hard to nail down, however, soome attributes of a high-performance building include:
Energy Efficiency, Lower Cost of Ownership, Accessibility, Health and Safety, Beauty, and Sound Building Science.
Different designers and consumers in the building industry tend to place higher emphasis on a few of the attributes above, while perhaps ignoring or minimizing the importance of others. So, the definition of High Performance will vary from person to person. A team approach, with design-phase involvement of all parties, is key to tailoring the priorities to fit a specific project's goals.
Some aspects that deserve careful consideration include:
Scale (square footage, volume, etc.), Siting (location, orientation, solar exposure, weather exposure, etc.), Construction methods/Material selection, Mechanical systems (heating, cooling, ventilation), Thermal performance (Insulation, thermal massing, glazing), Indoor Air Quality (passive and/or mechanical ventilation, material choices that minimize off-gassing, etc.), Moisture Management (both vapor and liquid), Energy Use/Energy Production (efficient designs/ solar arrays...etc.), Accessibility and Integration of Outdoor Spaces. And the list goes on...
From the high-performance building projects I’ve been a part of, I’ve gained insights into some methods and materials that work well, some design elements that are easier or more difficult to include, and some things I will be sure to recommend or warn against. I'm excited to share these experiences in future projects.
I believe we owe it to ourselves and to future generations to build intelligent, efficient, healthy, durable, and beautiful structures.
A very high performance home, with classic architectural details. Wood siding as well as stone are built over a ventilated rain screen to allow any condensation to escape. With extra thick walls, water vapor is very important to handle correctly. Walls are double 2x4 construction, with an additional 4" of rigid foam outside of an airtight envelope. R-values are more than double the code minimum. Very little heating is needed, and the house is very quiet and comfortable year round.
"Modern-Rustic" details, with high performance underneath. Hydronic heated concrete slabs on both upper and lower floors, a sizable solar array, Heat Recovery Ventilators, and more. Use of non-toxic material was a priority on this build as well.
High performance starts below grade. This foundation is literally built ON foam. Six inches of dense EPS-39 Geo-foam was used under the concrete footings. Less dense EPS-22 was used to completely isolate the stem walls and slabs from the outside environment, and soil contact. Though somewhat labor intensive, studies have shown significant energy savings over traditional foundations.
After the foam, a durable (15 or 20 mil) vapor barrier is installed, and then hydronic heat tubing tied to a re-bar grid. The air tight vapor barrier is taped and sealed with attention to detail, particularly around penetrations, then connected to the airtight barrier in the wall systems and ceiling/roof system, creating a complete, continuous air tight envelope.
Knock-out form for a single person elevator. Hydronic heat zones can also be seen here, indicated in spray paint.
With all inspections passed, and all tubing and plumbing lines holding pressure, it's time to pour concrete.
Fresh poured slab.
Another super insulated foundation. Note the stacks of EPS foam in the background.
A novel use of Geo Foam. 2ft x 4ft x 8ft blocks of EPS- 39 were used here to drastically reduce the soil pressure of backfill behind the partial basement level. The blocks were "bleacher stacked" behind the 10ft. basement wall at a 1:2 rise/run ratio, and then buried under compacted structural fill material. As a result, a lighter and simpler engineered retaining wall could be used, eliminating substantial concrete and steel.
A high tech home in the making.
Double checking and documenting the layout of the future kitchen island. Wood knock-outs can be seen here that will allow plumbing, duct work, and wiring to enter the island without drilling the slab (or hitting heat tubes) from below. With so many mechanical systems that will later be conceled, "as-built" photos are important to have on file.
Here, the air tight Zip sheathing layer is nearly complete. Seams are taped and nail holes are sealed. You can see the extra deep window bucks, ready to allow another 4" of wall depth.
Manufactured on site, per an engineer's spec, "Z-joist" are installed vertically to allow natural ventilation with warming and cooling cycles. Attached back to the framing, they are strong enough to carry a sone veneer. While this was indeed an effective method, I've since become convinced there are more efficient, and therefor more affordable, methods of building super insulated wall systems.
Two layers of 2" rigid XPS closed cell foam are installed between the Z joists, and then taped and sealed with a weather resistant yet breathable tape, similar to a Gore-Tex ski jacket, but with an adhesive backing. Almost ready for siding here, but first, we performed a blower door test and used an infra-red camera to find and fix any air leaks. There weren't many, but we found a few and sealed them. A house this tight requires mechanical ventilation, typically some type of HRV (heat recovery ventilator). In this case, we used a Zender ERV (energy recovery ventilator). It runs constantly at very low CFMs, and uses heat exchangers to collect and re-use heat. It provides a constant supply of fresh air, and is also filters particulates and allergens from the incoming air.
Second story radiant slabs are 3 inch thick concrete. While some homes use Gyp-Crete, and are poured only 1- 1/2" thick or sometimes even less, the added thermal mass helps keep the home a constant temperature. Also, the concrete can be stained, polished, and sealed for a beautiful finished floor.
Aways good to get the roof on. The taped and sealed "Zip" sheathing can be seen here as well.
Not as insulated as some high performance homes, this client opted for using solar panels on the roof to offset their energy requirements. Still, to increase the R- value and eliminate thermal bridging, 2" of XPS foam was installed under the siding.