Passive House - Earth Day News · Apr 22, 04:07 PM
Today is Earth Day, and it seems an auspicious time to announce a groundbreaking event… in both senses of that word. On May 24 our first Passive House, and the first Passive House in the DC metro area will begin to take shape on North Chelsea Lane in Bethesda, Maryland. Twelve years ago our firm began the transition toward sustainable design. It has been quite an adventure, and with the construction of this home, we will finally have reached our goal.
We are calling the project The New American Foursquare. Our goal for this first house is to demonstrate that Passive House construction can be mainstream construction, both in terms of cost and design. On the cost side, the house will cost roughly $225 per square foot, exclusive of land costs – which places it squarely in middle range of high quality custom homes. With regard to design, our influence is the original American Foursquare, developed a hundred years ago by Sears Roebuck as the new house for a growing middle class. You have seen them up and down the Main Streets and Elm Streets of most every American town and city. They were designed to be economical to build and efficient with regard to space. These same principles make them well-suited for Passive House construction. The nearly perfect cubic volume is close to ideal in terms of surface-to-volume ratio, and its efficient layout allows for the short plumbing and ducting runs that are intrinsic to good Passive House design.
the team
We have put together quite a team to make this happen. O’Neill Development Corporation, a Gaithersburg-based firm with whom we have worked over the past 20 years, is both the developer and the general contractor. It is the vision of the O’Neills that is turning this dream into reality. One of the best builders in the area, with long-established reputation for value, fine construction and excellent design, they are the ideal partner to bring this highly collaborative project to life. Similarly, the key subcontractors on the project are leaders in each of their areas of building expertise: Panelwrights, the leading SIP provider in the mid-Atlantic region, will construct the entire building envelope and guarantee it to meet the stringent Passive House air infiltration standards. Foley Mechanical, voted 2009 National Residential HVAC Contractor of the Year by the Plumbing- Heating- Cooling Contractors Association, will handle all ventilation and hot water systems. Michael Lebeau, of Conservation Technologies, one of the leading Passive House mechanical system designers in the country, will consult in developing the design that Foley will implement.
the building envelope
While outwardly traditional, what makes this house unique is its exterior envelope. It will be essentially airtight—tighter by roughly a factor of ten than an EnergyStar home. Windows will be triple-glazed Canadian units with insulated frames. Walls and roof will be made of SIP construction, a system we have used on several projects already. Basement walls will be standard concrete, but detailed meticulously to eliminate thermal bridging. While most elements of this house will be of tried-and true systems, there is an important difference: they will linked together into a completely integrated whole-house approach, which is essential to affordable sustainable design. The key to the integrated design is the Passive House energy modeling software, but that is the subject for another blog post.
so where are the PV’s?
Unlike most houses wearing the green label, you won’t find a lot of solar panels on the roof of this house. This is because Passive House construction approaches the energy equation by reducing energy demand, not by using costly renewables to offset fossil fuel supply. We are, however, making the roof solar-ready for both photovoltaics and solar hot water, with conduits and piping pre-installed so that the future owners can take the house off the grid if they choose —something quite easy to do with a Passive House. After all, when you are using 10% of the energy used to heat and cool a standard house, it doesn’t take very many PV panels to achieve net-zero.
interiors and comfort
The interior of the house will be indistinguishable from a standard house. Kitchen and laundry appliances will all be EnergyStar rated. Bathrooms will have standard water saving plumbing fixtures. Interior products—from construction glues and paints to cabinets and countertops— will be non-polluting of interior air and sustainably manufactured, producing an interior environment both attractive and healthy.
While the house won’t look different from a traditional home, you will clearly feel a difference from the moment you walk inside this house. Passive Houses are exceptionally quiet and comfortable. There is no stratification of air; there are no drafts, there is no feeling being hot or cold when standing next to a window. Consistently in European surveys (where over 20,000 Passive Houses have now been certified), it is the comfort of these houses most remarked upon by their owners.
The story of the O’Neill’s visit to a recently completed Passive House in Illinois is instructive. Like any good builder, Brendan wasn’t about to embark on building a Passive House until he’d seen and touched one. So he and Brendan Jr. got on a plane in mid December to go out to Urbana, Illinois where two had been completed over the past several years. Unfortunately—or fortunately—they arrived in a full Midwest blizzard, with driving winds and temperatures in the low teens. It was stepping into those houses, and feeling how warm and comfortable they were that made him a believer. And it was when he peeked inside the mechanical room, and saw that the system was barely running at all that he said, “We’ve got to build these!”
health
Even more important than comfort, this will be a healthier house. Interior air quality of Passive Houses has been tested consistently to be healthier than in standard houses. The reason is simple: all the air you breathe is fresh and filtered. While normal houses recycle the same air around and around through the duct system, the Passive House ventilation system sends the air on a one-way trip through the house, so there is no build up of CO2 or other unhealthy gases.
heating and cooling
The one place inside the house where you might notice a difference from traditional homes will be when you visit the mechanical room; you won’t find a standard furnace or air conditioning unit. Because so little energy moves through the building envelope, a traditional heating and cooling system is unnecessary. Instead, you will find an energy recovery ventilator that brings in the fresh air distributes it through the house and exhausts it, transferring the heat or cold of the exhausted air to the fresh air coming in. The minimal heating requirements of the house in winter will be provided literally from the body heat of the occupants, the heat from the various electrical appliances, and supplemented by a small additional amount of heat taken from the hot water heater— equivalent to the energy of a hair dryer. In summer, several small mini-split heat pumps will handle cooling and dehumidification needs, using the equivalent energy of your car air conditioner.
The present house on the site, too small and in too rough a condition to renovate economically on such a valuable site, will be removed. Rather than hiring a demolition contractor, it will be dismantled in coordination with Diamond Waste Services and Second Chance. All wood, metals, glass, roofing, masonry and concrete will be recycled.
Dismantling is underway. Keep checking this blog for updates!
All inquiries are welcome. Our goal is to see these houses become the norm for truly sustainable homes. And did I say that this house will use 10% of the heating and cooling energy of a standard code built home?!
Inquiries from prospective buyers should be addressed to Brendan O’Neill, Jr. at O’Neill Development Corporation.
— David Peabody
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