The construction industry this year dedicated its recent annual trade fair, Batibouw, to energy-efficient building and renovation. Flanders is running ahead of the rest of Belgium (but not the rest of Europe) in implementing new rules on energy performance for new houses.

There are numerous interesting pilot projects, like the construction of 700 green social houses in Sint-Niklaas planned for 2012. And the banks have been asked to bring forward ideas on how to make it easier for homeowners to finance the building of lower-energy homes. Flanders Today takes a look at the latest hot subject in housing.

The energy level of a building is calculated according to the Energy Performance and Interior Climate (EPB) index, which calculates the effects of a number of factors – insulation, ventilation, solar heating, the efficiency of central heating, etc — to give an E-number. The lower the E-number, the more efficient the building. Each new house construction has to stay below a certain maximum E-number, which varies between regions.

In Flanders, all new homes have since 2010 been required to conform to an E-number of 80 or lower. In 2014, the limit goes down to E-60. In Brussels, an E-90 limit came into force in 2009 and will fall to E-70 in July this year.

How the E-number is reached is a matter for the owner, the contractor and the architect, who may prefer to give preference to one or other aspect of the house’s performance, as long as the final E-number is within the limit.

There are also specific maximum values for insulation (the K-number) and for ventilation. There are various levels of energy efficiency, reflected in the net amount of energy a house consumes. Existing properties, not subject to the E-limits, use about 270 kilowatt- hours (kWh) of energy per year for every square metre of surface area, with 200 of that accounted for by heating. The E-80 standard applied in Flanders comes with an annual consumption of 160 kWh per square metre, including 120 for heating. While an energy-saving house uses a maximum of 30 kWh per square metre, a so-called “passive” house has a consumption of only 15 kWh.

Keeping up with the neighbours?
On the whole, Belgium does less well on the energy efficiency of its homes, compared to other countries. The Scandinavian countries are far ahead on this score; in Norway, homes will have to come in at E-40 by next year. In the Netherlands, all new constructions from this year have to conform to a maximum of E-45, and the aim is to cut the energy consumption of existing houses in half by 2020. To achieve the same level as that, Belgium would have to cut consumption by 75%.

There are three main reasons why Belgium falls behind: a large number of old, badly insulated houses; a much higher proportion of detached houses; and a tendency to build large houses. Aside from the demands of the new E-level requirements, architects are receiving more and more requests for houses that are more energy-efficient, according to architect Anja Vissers, who has a practice in Herentals. “People want low-energy houses, though we don't usually go as far as passive constructions yet,” she says. “The trouble is, people haven’t got the budget; it costs more to build a low-energy house, and the time it takes to recoup the cost depends on many elements.”

Many architects, too, are just not up to date on the latest techniques and technologies. “Some architect organisations have arranged courses, but the training is limited. You basically have to make sure you keep yourself up to date,” explains Vissers. “There’s also the problem of contractors who aren't aware of new developments.”

Paying the bill
Flemish housing minister Freya Van den Bossche has asked the banks for proposals on offering energy-friendly mortgages to home-owners to cover the extra investment required by low-energy construction. According to her office, stricter requirements on energy consumption (see box) could increase the initial cost of building a house by 10 to 20%. But that cost will be recouped over time by the savings made on fuel.

“The total living cost is the sum of the mortgage and the energy bill,” says Van den Bossche. “Anyone who spends more on an energy-efficient house at the outset will pay less on energy bills for the rest of their lives. So it makes sense to allow a larger mortgage for houses like that.” After receiving proposals, Van den Bossche will bring the matter up with her counterparts from the other two regions, with a view to a system that covers the whole country.

In addition, The Brussels Region has set aside €5.3 million for training in the construction of low-energy houses. The region requires 70,000 new houses between now and 2020 to cope with population growth, and reckons the building programme could provide more than 2,500 new jobs.

Improving energy efficiency
Aside from technological contributions to efficiency such as boilers, solar panels and heat-exchange systems, a few simple principles go a long way to cutting the energy consumption of a house.
> Adopt a compact construction, where the ratio of interior volume to surface area is higher, thus reducing heat loss. One striking feature of the design of new low-energy houses is the recurrence of the cube form, which is a more efficient design compared to a rectangular form of the same volume (see sidebar). The absolute ideal shape, incidentally, is the hemisphere, the form of the igloo and the Mongolian yurt, ancient designs based on a perfect – and essential – understanding of energy efficiency.
> A semi-detached house loses less heat than a detached house, and a row-house less still.
> South-facing walls should include a large area of glass to take in sunlight, while north walls need to be properly insulated
> Some building materials are better than others at absorbing and retaining heat, such as brick, sandstone and granite.

Getting Help

To help you find your way through the thickets of new legal requirements and technologies, various websites point the way to experienced professionals.

www.ecobouwers.be has a database of hundreds of architects, advisers and suppliers across Flanders. Ecobouwers is an initiative of the Better Environment Union (BBL) and is supported by the Flemish Region.

www.energiebewustarchitect.be also allows you to search for a trained architect according to postcode. The site was created by the architect federations NAV and BVA and the Flemish Energy Agency.

www.lne.be/bouwgezond was launched last month by Flemish environment minister Joke Schauvliege and offers advice on everything from building materials, paints and floor coverings to how best to ventilate your home.

The E-Cube takes on the world

The E-Cube was developed by students at the University of Ghent for the Solar Decathlon organised by the US Department of Energy, a contest that brings together teams from schools across the world. The Solar Decathlon’s purpose is to develop ideas for cost-effective, energy-efficient and visually appealing solar-powered houses.

The E-Cube meets “passive house” standards and comes in the form of a DIY kit, which can be put together without special skills or tools. The basic kit can be extended and upgraded according to the client’s wishes, which makes it possible for a young couple, for example, to start off with the basic minimum and add to it as time goes on. “The E-Cube is more affordable because the costs can be spread over time,” explains the team, “allowing the client to finish off the house according to his or her own timing and budget.” www.solardecathlon.ugent.be