COPENHAGEN -- When Kay Helt moved into his superefficient home on the outskirts of Copenhagen two years ago, he felt as if he had just stepped into the lifestyle of the future. His high-tech house uses five times less energy for heating than his old one, and it recycles rainwater for the toilets and shower.
Yet in only a few years, Helt's house will already be obsolete.
With various degrees of urgency, E.U. countries are moving toward requiring new homes to only use clean energy and have zero net carbon emissions, despite some real estate developers' complaints that such homes cost more to build and will be harder to sell.
The United Kingdom mandates all new homes be zero-carbon by 2016. France and Germany are debating stronger building requirements of their own. And Denmark will require all new houses to meet the "passive house" standard by 2020, meaning using 85 percent less energy and producing 95 percent less carbon dioxide than regular houses.
Such houses already exist all over the continent, some only a stone's throw away from Helt's, in a development kick-started by idealistic and determined local officials who thought the Danish central government wasn't pushing hard enough for efficient housing.
In 1977, Denmark was the first country to set what were then demanding energy efficiency requirements for buildings. But by 2003, the law no longer seemed so progressive to the local council in the county of Egedal. Since Egedal wasn't allowed at the time to set its own local building standards, the council decided to go into the real estate development business.
It bought 76 hectares of land in Stenløse, 17 miles northwest of Copenhagen, and resold it to developers and private citizens under the condition that all 750 buildings to be eventually erected there would be much more energy frugal compared to the national standards in Denmark. When finished, the development will save 630 tons of CO2 and 3.6 million kWh per year compared to a conventional neighborhood of its size.
Willy Eliasen, a former police detective, was mayor of Egedal at the time. He now serves as deputy mayor, and is spearheading the effort to turn Stenløse into Europe's largest low-energy development. "It's important that it's for ordinary people, not just rich people," he said as he proudly showed off Stenløse to a visitor.
Indeed, Stenløse looks like any other suburb, with cul-de-sacs, Danish flags hoisted on white porches, a large park in the middle, a kindergarten and a senior citizen center. People who want to move here can select a pre-approved house blueprint, or they can bring their own plan to be certified as low-energy.
The first two stages of the development, which included Helt's house, consisted of 350 buildings that were 25 percent more efficient than the current Danish building standard. Phases three and four are under construction now, with some buildings 50 percent and others 100 percent more efficient, including some passive houses.
The fifth phase will be only passive houses. Buildings in the last three stages will be equipped with 3 square meters of solar panels each.
Street lights here use low-energy bulbs. The salt spread on the roads during winter is specially formulated so as not to spoil groundwater. Polyvinyl chloride pipes and pressure-creosoted wood are banned.
It costs the equivalent of $96 per square meter more to build this way, but Eliasen is convinced that government mandates would push the price down. "Builders won't offer efficient houses unless required by law, for fear of losing clients to cheaper alternatives," he said.
But the cost of building efficient houses is dropping as contractors learn how to do it better and in less time. It took workers three weeks to build the first floor of the first house in the development. By the time they got to Helt's house, they performed the same work in two days.
Helt paid 2.3 million Danish crowns (about $450,000) for his two-story, 137-square-meter (1,475-square-foot) house -- a small premium for houses this size in his area, but a bargain compared to older houses closer to Copenhagen.
"We've chosen to live here because it fits our lifestyle," he said. "We love the fact that the house recycles rainwater, and we love the savings on utility bills. But of course we also like the fact that it's trendy now to be 'green.'"
Thick walls, shutters and a good ventilation system
Some critics say superefficient houses are too insulated, making the inside air stale. But Helt said he has never experienced this. As long as the house's automatic ventilation system is properly calibrated, stale air -- which contains too much CO2 from humans' breathing -- should never be a problem, experts say.
Helt's house has thick walls full of state-of-the-art Rockwool insulation designed to keep the temperature a constant 24 degrees Celsius (75 degrees Fahrenheit) inside, whether it's summer or winter. It is tested regularly to make sure it is airtight. The ventilation system keeps the air fresh and also takes out the humidity.
Houses face south or southwest and are equipped with thermal windows with shutters that go down to preserve heat in the winter and coolness in the summer. For a little extra money, a house can be designed to control the indoor climate automatically -- insulating from the cold, keeping heat out or providing ventilation as needed.
"We want to maintain high standards of living but at the same time reduce the CO2 emissions," said Jorgen Tang-Jensen, CEO of the Danish window manufacturer Velux, which supplies the windows in Stenløse.
"You take daylight much more into consideration, and when you talk of energy efficiency, you have to consider the building as a whole, not just individual components," he said. "Strict demands for components won't work for the whole house. After the oil crises of the 1970s, we started building with small windows. But the indoor climate was bad, and nobody wanted to live in those buildings."
Slashing heating bills by 80%
Helt said he paid only 3,800 Danish crowns for heat in his first year in his new house, compared to the 20,000 crowns he used to pay in his old house, which was of comparable size. "I had a house built in 1963 that was poorly insulated," he said. "That's a lot of money to save on heat, and I save even more by using less water, as well."
Rainwater is collected in two underground tanks, each the size of a bus. The tanks supply Helt and three of his neighbors with water for the shower and toilet, while drinking water still comes from the local utility. The neighborhood saves 23,000 cubic meters of water per year.
Solar panels and photovoltaic cells can provide hot water and some electricity. "Solar energy offers great potential for decreasing house CO2 emissions," Tang-Jensen said. "Up to 70 percent of hot water needs can be covered this way, and with a very short payback time. However, it's not financially feasible to use solar power for air conditioning."
To meet its goal of cutting 80 percent of carbon dioxide emissions by 2050, Britain will require all new homes to be zero carbon from 2016 and is considering plans to make all new commercial buildings zero carbon from 2019. A zero-carbon home gets the little power it needs from clean sources and on average returns to the grid as much power as it takes.
Home energy use accounts for 27 percent of British carbon dioxide emissions, with commercial buildings adding another 18 percent. If all U.K. buildings were zero carbon, the country would eliminate nearly half of its carbon emissions.
The Department of Energy and Climate Change says it also wants older buildings to be refurbished to become zero carbon by 2050, but so far, it has only proposed voluntary measures, much to the dismay of some environmentalists, as well as building material companies, which need a new source of demand after last year's real estate market collapse.
The next frontier: older houses and buildings
"We need to look into all existing buildings," said Tang-Jensen. "New houses should be built with the latest technology, but we can never escape the 99 percent of the houses that are old. Renovation is important for reducing global emissions." Tang-Jensen lobbies for incentives such as cheap loans for owners to renovate their homes and make them more energy efficient.
Denmark briefly ran one such program earlier this year, when it provided 1.5 billion Danish crowns for home renovations. The funds were quickly snapped up by homeowners.
Tang-Jensen hopes the Copenhagen climate summit, at which international negotiators will attempt in December to agree to a treaty to succeed the Kyoto Protocol and curb world greenhouse gas emissions, will include some guidelines for green building standards.
"The codes have to be local, because climate is different all over the world, but we should put very strict limits on how much energy your house is allowed to consume," he said.
This idea resonates in France, which is proposing that all new buildings be passive houses by 2020. Meanwhile, in Germany, where the passive house concept originated in the 1980s, the new Reichstag building in Berlin produces its own energy. In Freiburg, the Solar Village features houses that make more energy than they consume, selling the surplus back to the grid.
Can the U.S. catch up?
Catching up with Europe's more energy-conservative standards would pay off big for the United States, according to a report the consulting firm McKinsey and Co. released last month. The report said the United States could save $1.2 trillion by 2020 and cut greenhouse emissions by 1.1 gigatons annually if it invested $520 billion in better building insulation and low-energy appliances.
Velux and Rockwool, another Danish company that is the second-largest insulation maker in the world, are also cooperating to build a carbon-neutral new natural sciences building for Copenhagen University. The three-story building, which is to be ready this fall, uses a combination of district heating, solar cells, solar thermal heating and cooling energy and seasonal heat storage.
"We wanted to make it so it doesn't need heating or cooling for 10 months of the year and then get a little help in January and July," Velux Project Manager Lone Feifer said. Heat stored in the summer in metal rods buried deep below the building is released again in the winter. The university had to strike a special deal with the district heating utility to return hot water back to the district system at 72 degrees Celsius instead of 75 degrees without paying a penalty.
Rockwool is also involved in building experimental low-energy houses in Italy, Austria and the Czech Republic. Since builders use local labor and Rockwool delivers insulation materials produced regionally, the cost of low-energy homes varies from country to country, with cheaper price tags in Eastern Europe than in Denmark, Rockwool said. A passive house built in the Czech Republic costs only $1,150 per square meter, according to Rockwool.