Dispatch from Austria

Posted Wednesday, June 8, 2011 in Sustainable Maine

Dispatch from Austria

This home, the Matson residence, shows the surprising nature of passive houses - they can have many windows, or as few as the builder wishes. Photo By Scott Shigley Photography. 


by Paul Kando

INNSBRUCK, Austria – Where else can you hear under the same roof about family homes in Austria, Germany, Slovakia, Slovenia, Latvia, Siberia, Swedish Arctic, Tokyo, Las Vegas, Shanghai and Dubai; a bank building in Santiago, Chile; schools in Minnesota, Germany and Austria; elder housing in Germany; a commercial building in Korea, a German retail store, brewery, restaurant; even whole new city neighborhoods, and more – all using only 10 percent of the energy their conventional counterparts use for heating?

The 15th International Passive House Conference, held here last weekend, gathered about a thousand building scientists, researchers and practitioners from 43 countries. There were over 100 presentations and nearly as many innovative technical and product exhibits in a concurrent trade show for designers, the building trades and the public. The conference dealt with how to adapt the passive house (PH) concept to various climates and building styles around the world.

My colleague Topher Belknap and I jumped at the chance when an invitation came last November for us to present a paper and participate in the conference. We were interested as home owners, taxpayers and building professionals in learning as much as we could  about how the PH concept can be adapted to buildings of various sizes in various climates and how local building traditions and techniques can be integrated with it.

Contemplating Maine fuel-oil prices as they hover near $4 per gallon, I find it hopeful that there exist over 32,000 family homes, apartment houses, schools and other buildings around the world with heating loads 90 percent smaller than ordinary buildings of similar size. If the average Maine house, which presently burns about 850 gallons of oil per year, could achieve similar energy savings, its annual heating bill (at $3.70 per gallon) would be reduced from last winter’s $3,145 to a mere $315. If similar savings could be achieved in our local school and municipal buildings, the pressure on our tax dollars would ease commensurately.

As a home energy auditor and longtime building researcher, I have a professional interest in energy matters. Mainers collectively spend around $100 million annually for fuel oil alone and often complain about not being able to afford upgrading their homes’ energy efficiency. Wouldn’t it be cool to have $90 million to split up amongst ourselves, year after year, until we all paid 90 percent less for heating than we will have to do forever?

But what is a 'passive house'?  

All buildings, large or small, are built to house something or someone. In this sense the word “house” means any building, not just a family residence. So the expression “passive house” refers to any building designed to provide not merely shelter but also indoor comfort. But why the “passive” label? 

From the time homo sapiens emerged from the cave, houses were built from whatever local materials were available. Not surprisingly, they reflect the local climate and its resources as well as the local culture. As any traveler knows, houses are characteristic of a place or region. No one will mistake a photo of a New England village for one in the Swiss Alps or on the Russian plain. Part of a place’s character derives from the materials from which houses are built: field stone, wood, bamboo, animal hides, willow branches woven between stakes and coated with mud Clay fired into bricks has been a favorite material with which to build structures that last for centuries. Bedouin tents, igloos constructed of blocks of snow and ice, and log cabins immediately suggest both place and culture. Yet on a functional level all houses are just shelters built to protect their occupants from the elements and provide them with a measure of comfort.

In most places that comfort comes at a price. For much of the year it is either too cold or too hot outside. It is not enough to keep out the wind and snow. One must most likely also find a way to heat the place during the cold months. Over the centuries man has come up with a variety of ways to warm his house, usually by burning some type of fuel. Over time his techniques improved from burning sticks and dried dung in open pits and fireplaces; he graduated to stoves, furnaces, high efficiency boilers and electric heat pumps. He discovered central heating and, after virtually deforesting much of the developed world, abandoned firewood in favor of coal and ultimately oil and natural gas.

But no matter how we heat our homes, we must be actively involved in procuring and delivering fuel, stoking and controlling the fire, maintaining equipment, dealing with ashes, soot and the effluents from the chimney. We must open and close windows, turn fans on and off and change our wardrobe from summer to winter and back again year after year. In short, to be comfortable, a traditional house requires us to be active in making up for the inherent inefficiency of the house itself. And improving the energy efficiency of a conventional house means adding something as an afterthought: more insulation, better windows, air-sealing holes in the building envelope that should not have been there in the first place, replacing the heating system with a better performing one.

The passive house is fundamentally different. Rather than adding a collection of marginal improvements to an inherently inefficient structure, the designer or builder of a PH starts with a different question: Is it possible to build (or improve) a house so that the occupants do not need to be active in order to be comfortable? The answer is yes. And, once the science is understood, it's surprisingly simple. 

Technically speaking, PH is a performance standard for buildings so energy efficient that they require no conventional heating system. “The heat losses of the building are reduced so much that it hardly needs any heating at all. Passive heat sources like the sun, human occupants, household appliances and the heat from the stale air extracted by the ventilation system cover a large part of the heating demand. The remainder can be provided by the freshly warmed supply air drawn into the building. If such supply-air heating is enough, we call the building a passive house, explains Professor Wolfgang Feist, founding director of Germany’s Passivhaus Institut and head of the Department of Energy Efficient Construction and Building Physics here at Innsbruck University.

The devil in the details 

The PH concept is based on building physics and heat-transfer calculations facilitated by a computer-based analytical tool called the Passive House Planning Package (PHPP). The goal is to create a building that delivers maximum comfort, fresh air in all rooms year round, no increase in humidity or mold, all at very high energy efficiency and without relying on the actions of the occupants. In other words, a PH does not rely on changing human habits – or light bulbs. It will function efficiently regardless of the lifestyle of its inhabitants.

PH is neither a style nor a specific method of construction but a minimum performance standard a building has to meet. To an observer a PH is no different from any other building. The fact that most passive houses are new sometimes gives the false impression that they must be ultramodern in design. In fact, there are scores of centuries-old buildings that have been upgraded to meet the PH standard without altering their style and character.

At its core PH is simplicity itself: Instead of detailing specific levels of insulation and other requirements, it sets up a maximum energy budget which a building must strive to meet:

1. for heating and/or cooling no more than 15 kilowatt-hours (kWh) of energy (about 1.5 liters of heating oil) per square meter (m2) of floor space per year;

2. for all purposes (water heating, cooking, lighting, appliances and so on) no more than 120 kWh/m2 per year; and

3. as a minimum air-tightness standard, a PH must not have more than 0.6 air changes per hour at a measured indoor-outdoor pressure difference of 50 Pascals. (For reference, 1 square meter = 10.76 square feet)

These are calculable values and the PHPP encourages designers and builders to come up with the best combination of materials and techniques to achieve them. PH is an invitation to innovate and find creative solutions. The Passivhaus Institut and the International PH Association maintain a multilingual website dedicated to sharing innovative techniques from around the world. Not surprisingly, in practice many PH structures outperform the standard’s minimum requirements. At the same time, while only buildings that meet the above maximums are formally certified, practitioners are encouraged to use the PHPP to maximize energy efficiency in any building, even if it cannot meet PH standards.

A PH relies on exceptionally high levels of thermal insulation; well insulated, thermal-bridge-free window frames with triple low-e glazing; thermal bridge-free construction throughout; an airtight building envelope; and comfort ventilation with highly efficient heat recovery.

A key feature is a central ventilation system that recovers 80 to 90 percent of the heat from the exhaust air and transfers it to the incoming fresh air. The stale air is drawn from rooms where odors are likely (kitchen, bathroom, laundry) while the fresh air is supplied to the living rooms and bedrooms. PH ventilation systems are quiet, low-energy devices that deliver multiple benefits to the building’s occupants: a continuous supply of fresh air 24 hours a day; clean, allergen- and pollution-free air (thanks to effective filtering); and a comfortable, even air temperature. Odors and excess moisture are continually removed instead of spreading through the house. The air in the living and sleeping areas is always free of odors, excess moisture and mold. Because the air flow is constant, the air velocity is low, with no noise or uncomfortable drafts.

The seasonal heating energy demand is less than that needed to provide hot water to the household. Heating the living area thus can even become a convenient side effect of the hot water supply. While there are many ways to supply the needed heat, the most up-to-date PH systems employ an electric heat pump that draws its energy either from the fresh air supply entering through a ground heat exchanger or from brine circulating through an underground heat-exchange loop.

PH structures generally use electricity as their sole purchased energy. At the same time efficient appliances ensure that electric power consumption is minimized. The minimal power requirements can then be easily met by photovoltaic panels installed on the roof, turning a PH into a zero-energy building. In Germany and Austria, foremost among countries with Feed-in Tariff laws in place, many homes generate more electricity than they consume and sell the power back to the grid. Solar water heaters are also popular and can be easily integrated with the PH concept. And, according to one of the papers presented at the Innsbruck conference, the European Union is working on a “Near to Zero” pan-European Energy Policy for Buildings.   

What about cost? A PH-certified building in the United States currently costs 10 to 15 percent more to construct than its conventional equivalent, principally because some of the components (notably the windows) are difficult to find in this country and therefore expensive. On the other hand, the over 90 percent reduction in heating costs quickly makes up for the extra up-front expense. The owner of a similar three-bedroom conventional house winds up spending $50,000 to $60,000 more over the term of a typical home mortgage.

Costs are nevertheless important. If the choice is between affordability and formal PH certification, many of those who addressed this issue at the conference opted for a cost-effective “near-PH” building over a formally certified one.  

On balance, given our own combination of predicaments – an overheated planet, a troubled economy, extreme oil-dependency we can no longer afford – it seems simply stupid to build new buildings which fail to come as close as economically feasible to meeting the PH standard. 

Presenters at the Innsbruck conference reported on PH projects in regions raging from north of the Arctic Circle to Chile, Korea, China, Japan and Dubai, as well as Austria, Germany, France, Italy, Croatia, Slovenia, Slovakia, Latvia and Russia. Others spoke about ongoing research and policy development. The German cities of Heidelberg and Karlsruhe, for example, are developing large PH neighborhoods and use the PH approach as an economic and urban-development tool. Austria is developing a comprehensive research and development program dedicated to PH building components.

There were several presentations from the United States, covering projects in California, Colorado, Virginia, Minnesota and Maine, as well as a fascinating report on how the US Army is using the PH concept to develop energy-efficient military housing.

Outside the formal program and exhibits, conference participants could tour factories that produce such PH-certified products as specialized heat pumps and leak-free windows with insulation values greater than R-8, made to order in custom sizes. Among the many imaginative new products: advanced insulating panels that employ vacuum sealing and nanotechnology to achieve insulating values as high as R-30 per inch and do not outgas; load-bearing, crush-proof glass-foam insulation used under foundations and concrete slabs; and whisper-quiet whole house ventilation systems. The flexible electrical conduits with snap-fittings used in PH construction, along with round, rather than rectangular, electrical outlet and switch boxes are seamlessly snaked through the PH structure and air-sealed during construction. The wiring is inserted later. This, along with similarly flexible pipe runs, is an elegant way to prevent air leakage routinely introduced by American subcontractors who must drill their own way through a building.   

We visited a number of PH building projects scattered around Tyrol, and the occupants of several passive homes showed them off to us. A community kindergarten featured an adjustable shading system over its windowed south side, opening up to a green garden with cherry trees, play equipment and picnic tables. The shading is needed, it was explained, because a PH can overheat on a sunny day even when temperatures are below zero outside. The kindergarten and pre-school also housed a gym for adult use in the evening.

Connecting dots: The larger context

“Back in the 1970s the United States was way ahead of us,” observed a Swedish colleague during a conference lunch break, meaning to pay a compliment. “Then came 1980 and Reagan and, inexplicably to us, you guys stopped doing energy research. In many ways we were the beneficiaries.” Indeed, against the Hollywood stage-set of “morning in America”, many U.S. researchers had to choose between changing careers or going where they were more valued and appreciated. During the 1980s, the most advanced energy- and building-science research was carried out in Sweden. It attracted talent from the rest of Europe and the United States. The PH concept, too, was built on the foundation of Swedish building research by Professor Feist and Swedish colleague Bo Adamsson, who spent years refining it. I first met both in 1988 at a conference in Stockholm.

During that meeting, Dr. Jim Hansen of NASA gave riveting testimony about documented man-made global warming. With the first energy crises and oil-price shocks of the 1970s still fresh in memory, fledgling non-nuclear-energy research programs increased in importance worldwide. In the U.S., President Nixon established the Energy Research and Development Administration, which President Carter later elevated to the Cabinet-rank Department of Energy. Large research programs were initiated, focusing on all forms of renewable energy. However, it soon became obvious that renewable energy makes little sense when applied to buildings that waste much of their heat. Scientists at the federal Lawrence Berkeley Laboratory did yeoman work in this area before the Reagan administration drastically curtailed their program. Fortunately, much of that knowledge became available internationally. So, on that day in 1988 we listened intently as Feist and Adamsson made their case for the cheapest form of energy there is: the energy not used.

Then the Berlin wall fell and the European Union expanded to include several former Soviet bloc nations in Central Europe. With the growth of the EU, intra-European research cooperation increased as well. Research programs were initiated to provide funding for energy initiatives across the continent, including the EU’s Joule (1989-1992), Thermie (1994-1998) and combined Joule-Thermie (1999-2002) programs. The first PH buildings were a private residence in Germany and a multi-unit development near Gothenburg, Sweden. Both were thoroughly documented, demonstrating reductions in energy consumption on the order of 90 percent. Then, under the Thermie program, the European Commission’s Directorate-General for Transport and Energy launched a new program called CEPHEUS (for Cost Effective Passive Houses as European Standards), with the goal of demonstrating the feasibility of the PH concept across Europe. As a result, 271 PH housing units of assorted sizes were constructed in five European countries: Austria, France, Germany, Sweden and Switzerland. The program included rigorous, in-process scientific monitoring of each project, including an evaluation of building operations and performance through a systematic measurement procedure.

CEPHEUS demonstrated the technical feasibility of PH construction at a modest extra cost (recovering that extra investment from cost savings during use) in an array of different buildings in a variety of European locations. It demonstrated investor and purchaser acceptance of PH and even the feasibility of establishing PH as a building standard across Europe. It provided incentives for the design of energy- and cost-efficient buildings and the development and market introduction of innovative technologies that meet PH standards. It demonstrated that the PH standard is climate-neutral and meets the comfort requirements of new housing cost-efficiently, while producing zero greenhouse gas emissions. CEPHEUS also provided opportunities for both the lay and the expert public to experience PH hands-on at several sites in Europe, including at the EXPO 2000 World Exposition in Hanover, Germany. The PH concept has been spreading ever since.

An important side effect of European R&D programs has been the spread across European society of an ethic of managing energy and other resources more effectively. Europeans increasingly view energy conservation and renewable energy as keys to 21st century economic development. In hotels obvious energy conservation measures are everywhere, likely reflecting enlightened public policies. The lights and air conditioning in the guestrooms work only when activated by the room key-card. The hall lights are dark until turned on by a motion sensor. When leaving the room, the guest takes along the key-card, automatically turning off the room lights and the air conditioning and moving the ventilation system into conservation mode. At airports, subway and railway stations and in department stores escalators and people movers either stand still or run in super-slow standby-mode until someone approaches to use them.

In my travels I couldn’t help noticing the photovoltaic arrays on the roofs of houses, barns, industrial buildings and outbuildings. Germany and Austria have feed-in tariff laws that encourage decentralized power generation. Germany’s has been in effect over a decade by now. As a result Germany has become a world leader in the manufacture of PV modules and other types of renewable energy hardware and knowhow. Half a million permanent jobs have been created. Austria is not far behind and leads Europe in the percentage of houses equipped with solar water heaters and has the largest number of PH buildings per capita.

Why is it that, having tried twice, we were unable to pass a feed-in tariff law here in Maine, or at the federal level, even though a similar law has been a great success in nearby Ontario and recently even such Third World countries as Malaysia have put one on their books?

I couldn’t miss the impressive number of construction sites of not only housing and other buildings, but also major infrastructure projects like new roads and rail lines. At our conference, a parade of public officials – deputy governor, mayor, federal minister of Transportation and Technology, spokesperson for the European Commission – spoke of economic development, funding and incentives, the importance of energy and resource conservation and saving the planet from the ill effects of anthropogenic greenhouse gas emissions. Nobody, throughout the whole conference, ever mentioned deficits, budget cuts or tax cuts.

What about Maine’s existing houses?

Can our old frame houses be cost-effectively upgraded to PH performance? This question has been the subject of our own research here at the Damariscotta-based Midcoast Green Collaborative and was the subject of our paper in Innsbruck. It began when my colleague Topher Belknap and I decided to offer energy audits to area homeowners and found that all the available computer software fell short of our expectations. So Topher wrote a new energy audit software, incorporating key features of the PHPP and enabling us, unlike other home energy auditors, to evaluate each audited house in terms of PH principles and provide energy-upgrade recommendations consistent with PH performance as the ultimate goal.

Having conducted over 200 home energy audits, we have built a large database about area houses. Each and every energy audit helps us improve the advice and recommendations we offer. (We do not implement our own recommendations. Using an energy audit as a marketing tool to sell a home rehab job suggests a conflict of interest.) Our research shows that the energy consumption of typical houses we have audited– many of them 19th century structures – can be reduced by 50 percent to 80 percent, in most cases without major renovation, often by means of simple repair-type steps well within the competence of the average homeowner. Of course, it is possible to farm this work out to a competent contractor and get the work done with dispatch. However, for those of us not in the financial position to do so, it is comforting to know that we can upgrade our homes gradually to near-PH levels, using our own labor (or pooling our labor with that of our neighbors), on a schedule of our own choosing.  

The typical old Maine farmhouse may never fully meet the performance requirements of a new PH at a reasonable cost, but it can come close. The technology is available. Motivated owners who recognize that it will cost more not to do all they can to upgrade their energy-leaky properties can succeed. The question is will they have to do this in isolation, or will a more enlightened public policy environment, committed to solve our common problems, help them in this endeavor?

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