The buyers of these brand new apartments outside Trondheim in Norway are about to move in to apartments featuring insulation that is superior to that in other newly built homes. The apartment complex also uses super insulated windows, ventilation with heat recovery and an advanced heat pump system for domestic hot water. All these features are controlled by a modern, user-friendly Internet- based operating system.
But if you are thinking that all the insulation and technical extras will be hard on the wallet, then you are wrong. These residents will enjoy lower monthly living expenses than those who build new, but without efficiency investments.
The property developer has calculated that construction costs are about six percent higher than normal. However, SINTEF research scientist Tor Helge Dokka, the building project’s specialist advisor on energy and indoor climate, says that homeowners will be well compensated for the extra expense by the savings from reduced energy consumption.
The apartments have an annual energy consumption of just 70 kilowatt hours per square metre. The average annual energy consumption in Norwegian homes is around 200 kilowatt hours per square metre.
On an annual basis, the low-energy apartments require a miserly 18-20 kilowatt hours per square metre for heating – just one-fifth of the normal level.
HERE IS THE RECIPE
Dokka is quick to emphasise that the energy savings are not achieved at the expense of the indoor climate or comfort level. The recipe for such efficient comfort comes from a host of initiatives:
- The walls, floor and roof of the apartment complex all have greater insulation than normal.
- The windows are super insulated but, when desirable, can allow in considerable radiation heat from the sun. ?The building structure has no air infiltration or thermal bridges.
- Each apartment has a separate ventilation system supplying adequate fresh air. The system recovers 70-75 percent of the heat in the extracted air.
- Low-energy lighting is used where possible to reduce energy consumption and prevent overheating.
- At any time, you can view the current level of heat and electricity consumption on a graphic energy tracking system designed to increase consciousness of energy use.
- When the apartment is empty, several installations automatically switch to standby mode. Lighting, coffee percolators and the like switch off and the ventilation level automatically reduces.
The Trondheim apartments will not reign for long as the leader in energy saving. Several highly efficient “passive houses” are in the process of being built or in the planning stages. To qualify as a passive house, the annual heating requirements must be less than 15 kilowatt hours per square metre. That is just one-seventh to one-eighth of the heating requirements of a conventional home.
In addition, a significant percentage of the home’s heating requirements must be provided by renewable energy. In theory, such houses should not require heating and cooling systems. But, in practice, on the coldest days of winter ventilated air must be heated to some degree.
“Energy consumption in these passive houses is so low that it will soon be possible to meet the energy requirements exclusively from locally produced renewable energy – everything from combinations of solar collectors, photovoltaic cell units and wind turbines, to heat pumps and small bio-powered combined power and heating plants,” says Dokka.
By Svein Tønseth