Article by Joel Bartlett about Passive House
/Go back to 1972 or so when the first big "oil crisis" hit. Gasoline jumped from 30 cents a gallon to over a dollar overnight, and there was panic. The Federal Government assisted in funding alternative energy projects - wind-powered generators, solar panels, battery technology, thermal storage, and the like. In tandem with this, time-tested "passive architecture" principles (as distinguished from "active" systems) were introduced and became the vogue. The idea even then was to reduce the need for fossil fuels. (Too bad these efforts tapered off as people got used to paying more for oil! or we'd be much further along and not into a Global Warming crisis.)
Around 1985, I designed a house for a client in Bucks County twice the size of his current home and using half the energy! The Utility Co would not let me put in the properly-sized small boiler because they didn't believe my calculations for the heating load. Compare that with today, where they are encouraging all the energy-saving features a home owner or builder can afford to avoid having to build more power plants!
I did not tell the client about some of the features, I just did it, and the family loved the design. It wasn't until they moved in and got their first utility bill, thinking there was a big mistake, that I explained to them what I had done.
Here are some examples of "passive architecture" I used in that house:
The house was built on a south-facing slope, so I bermed the house into the hill. The bedrooms in the back had walls with the first 3' from the floor at a stabilized moderate temperature year-round. The uniform northern light and the view of the north fields were pleasant and attractive.
Casement windows - minimum two per room (and best at corners), to "scoop" outside air in and provide natural cross-ventilation.
Operable clerestory awning windows facing south - in combination with the casements - gave wonderful cross-ventilation, and practically eliminated the need for air conditioning or a "whole house fan." The southern light penetrated well into the house, greatly reducing artificial lighting.
I used black slate on the thick concrete floor behind high south-facing living room windows. I also had south-facing skylights above letting the sun heat up a dark-colored stone wall that incorporated the fireplace. (The client was a concrete contractor and in partnership with a stone mason, so cost was not an issue here!) The combination of these two sources of solar energy and its effective thermal storage resulted in the family not having to turn the heat on every night before they went to bed! ]
Overhangs and deep-set windows - allowing for tempering the intense summer sun, but letting it in on winter days.
I had them install operable thermal shades on sensors to capture all the heat gained during the day. The shades also could be controlled to reduce direct glare as required.
2x6 framed exterior walls were filled with insulation, vapor and air barriers for a tighter building envelope. This was better than the typical design of an exterior wall at the time, and reduced the size of the heating elements greatly.
I specified 2x10 framed roof joists filled with insulation, vapor and air barriers. Tremendous reducing of heat load, but the one big mistake I (and the contractor) made was not providing a larger air space between the insulation and the underside of the roof - the result was a wet drywall ceiling.
We had southern landscaping for shade - not only shielding the house from intense solar gain in the summer, but providing a wind break, to say nothing of the aesthetic aspect.
I used thermally insulated doors and windows - reducing the extreme temperature changes.
I employed light-colored roofing and siding materials, keeping the solar gain down while providing a pleasing aesthetic.
Hey, everybody! That was 1985, 30 years ago, and the same principles are used today (it's just that we old-timers remember that that's what a "passive house" meant then!) Add to that house the "active systems" which, unfortunately, had payback periods of up to 15-20 years at the time, and you were doing about as much as folks could. (By the way, my client did not go for the wind-powered generator or swimming pool heat sink with operable roof that I designed - "that will have to be Phase II!")
So, what's changed in 30 years? Well, first of all we have a world-wide climate crisis and Europe was far ahead of us in recognizing the problem and providing solutions to reduce the "carbon footprint." We didn't talk about carbon as a commodity when the first wave of solar energy research started in 1972, but soon it will be the "standard" by which we measure everything we are doing.
Second, with a public more educated about the problem, the Passive House (and alternative energy) is becoming more and more a marketable solution. Look around the neighborhoods at house sales - the ones with solar panels go fastest. Tell people their energy bills will be a fraction of their neighbor's and make it affordable for them to have this, and they will buy, with or without the social component.
But what about the argument that the air quality might be suspect if you perfect a tight building envelope? What about the argument that the up-front cost is prohibitive? And can Passive Houses actually be attractive, or are we stuck with rectilinear contemporary boxes out of Dwell magazine?
All these arguments need to be countered successfully, or we will not be able to build.
The lender wants a certification that we meet our specifications (as does the town, even though we are building homes that far exceed the current codes for insulation, air exchange, etc.)
The neighbors and the town (including the Historical Commission) want an attractive village that "fits in," and we want to be able to appeal to a broad cross-section of the public.
As far as the health issue, armed with plenty of recent research and case studies, the Passive House Institute of the US (PHIUS) has named standards, and industry is complying with them.
To combat cost, Altair actually has companies competing with each other to build our project, at least two of which say they can meet or beat the budget we established a couple of years ago for "stick-built" (on-site) construction.
Although the principles I used in 1985 still apply, much has changed, and there are several other energy-saving features in our homes:
The homes are small - a result of sharing common spaces in the Common House, and also the wish of home owners to "live lightly on the earth," i.e., with less stuff!
We are clustering the homes, and the common walls, along with shared shade plants, reduced outdoor lighting, and smaller footprints for exterior maintenance saves more energy
We are looking at a double-wall construction for the outside walls and the roofs. This means that the exterior insulation will not be penetrated by electrical or plumbing, and, by the way, we can put plumbing in the exterior walls.
We have a better design for the floor slab, roof edges, and the floor edges - the thermal envelope is 100% complete, as are the vapor and air barriers. Not only does this reduce fuel bills, it eliminates moisture in the walls, greatly reducing the presence of mold in the house (remember some of the horror stories about this?)
Windows and doors have gotten better, as have the installation and sealing techniques, the applied films, the hardware - everything about them. Naturally, we have to do a cost-benefit analysis balancing economy, efficiency, and aesthetics before we buy the latest triple-glazed window.
Heating, ventilating, and air conditioning technology has changed by light years. As little as two years ago, we were talking about geo-thermal water sourcing and radiant floors, both of which with Passive House design are costly and overkill. Now, we're talking about an Energy Recovery Ventilator, split system air source heating and cooling packages, modest controls for booster air offsetting the exhausts, and Smart Technology.
It's all electric, and each home can generate its own electricity now that photovoltaic roof panels have gotten more efficient and have come down in cost. (However, each home will need a separate meter, because PA legislation with the PUC's do not allow for "community solar systems.") No more use of fossil fuels! (although we have to look at what fossil fuels were used to make the products and building materials we propose to use).
Safer materials are available - improved insulation, low VOC's, more reclaimed or recycled, products made in factories powered by alternatives to fossil fuels, and less wasteful production and packaging.
More durable materials are available and the prices of some materials have gone down - for example, shingles now have long warranties, attractive cementitious siding (Hardie plank, etc) lasts longer, composite "woods" have become readily available in a variety of profiles, textures, etc, flooring options, especially bamboo, have exploded - just to name a few.
Hot water heat pumps and heat pump clothes dryers are now available.
Efficient electric induction stoves are becoming affordable.
Light-emitting diode (LED) and compact fluorescent lighting have revolutionized the industry and have tremendous flexibility for both interior and exterior applications, though we need to look at some of the studies coming out regarding environmental pollution.
We didn't have cell phones in 1985! Now, if we choose, we can control everything through low-voltage networks or wireless technology right on our Smart Phones. Controls, computers, monitoring - everything is smaller, more user-friendly, and cost-effective, and there are more companies in the market. Integrated systems are not far away. Again, we need to balance this with folks’ sensitivity to EMF’s.
Very significant is the fact that factory-built housing has become a successful industry. Although US companies are lagging behind say, Sweden, which has 70% of its new housing built in factories, panels, components, and sometimes whole boxes are becoming more commonplace. Couple this with modular design, and you have tremendous efficiency.
Here are some of the reasons factory-built homes are better: Quality control is hugely important in maximizing the tightness of the building. Speed of installation in the field saves a tremendous amount of money. To give an example, the Passive House affordable housing project under construction on Rt 724 in Spring City ("Whitehall") is taking four months less to build than traditional construction. This results in less interest payments to lenders, rental income available sooner to the investors, almost negligible damage to the buildings (much less exposure to the elements before the building is water tight).
These are just a few of the things that have changed in passive house design since I drew that house in Bucks County 30 years ago.
We still have a lot to learn about Passive Houses, who to build them, what they will look like, and what they'll cost, but we are convinced it is the way to go. Join one of our Passive House seminars or tours. Ask about the Philadelphia Chapter of PHIUS and their activities or go on the national website at phius.org.