One radiator to heat a whole floor

January 12, 2017, Norwegian University of Science and Technology
Maria Justo-Alonso and Laurent Georges have studied small houses and apartments that have been built based on Norway’s passive house standards and with a reduced number of radiators on each level. Credit: NTNU

Saving energy from building highly insulated homes—often called passive homes or zero-emissions homes—makes sense for the climate and for the homeowner's pocketbook. But what happens if your efficient home is a little too efficient, and parts are too warm?

Better-insulated homes have less , which reduces the space-heating needs and the demands on the building's heating system. Super-insulated homes like passive houses or zero-emissions buildings (ZEBs) decrease the heating demand so much that you don't need to place a heater in every room or in front of every window.

In a new study, researchers at the Norwegian University of Science and Technology (NTNU) and SINTEF, Scandinavia's largest independent research institute, investigated the energy performance of row houses and apartments built according to the Norwegian passive house standard and with a reduced number of radiators.

"Our goal has been to find a good balance between energy efficiency and user satisfaction with temperature and comfort, says associate professor Laurent Georges at NTNU's Department of Energy and Process Engineering.

"With only one radiator per floor, you might expect that users would find the rooms without radiators too cold, but we found the opposite. The overall thermal comfort in the living areas was good. The challenge was more that people who prefer cold bedrooms found the bedrooms too warm," he says.

Simulated, measured and interviewed

The researchers studied two apartments and two row houses built to the Norwegian passive house standards. They made computer simulations of the buildings to figure out the optimal way to adjust the and meet user expectations in all the different rooms. Field measurements taken in the buildings recorded the air intake temperatures, ambient temperature, air supply and heat recovery. And researchers interviewed the residents.

This heating method is called simplified heat distribution. Having one radiator per floor – in concert with a balanced ventilation system – reduces installation and material costs, and decreases heat loss from the ductwork by shortening the length of ducts needed.

Passive house design frees you from worrying about uncomfortable drafts from bad windows or cold exterior walls and means you don't need to place a radiator in front of each window. And because the supply air is intended to distribute the temperature more evenly throughout the rooms, you only need one radiator for multiple rooms, or one radiator per floor.

Bedrooms "too warm"

With a simplified heat distribution system, people who want a warm bedroom can have it, especially if they keep the internal doors open.

"Several participants in our study complained of overheated bedrooms. Norwegians usually want cool bedrooms (below 16 ° C). This doesn't work without opening the windows, even if they keep the bedroom door closed all day," says researcher Maria Justo-Alonso at SINTEF.

"Unfortunately, this way of regulating the bedroom temperature has major consequences for the heating needs for the entire house," she says.

Researchers have examined several strategies to adjust how individual rooms are heated.

Better for office buildings?

"We achieved our goal of simplified space heating, since most participants were satisfied with the overall room temperature. But we stumbled across another challenge – that it's difficult to zone for multiple temperatures inside the apartment if residents want that," says Georges.

Currently the researchers are working on solutions to lower the temperature of bedrooms in these kinds of housing units, without increasing the total energy use in the home.

Justo-Alonso and Georges' study also raises questions as to whether it is possible to use preheated ventilation air as the only form of heating in passive and other homes with low heating needs, since this leads to even higher bedroom temperatures. On the other hand, recent studies show that centralized air heating may be a good option for office buildings.

Explore further: 10 ways to keep your house warm (and save money) this winter

More information: Laurent Georges et al. Simplified Space-heating Distribution Using Radiators in Super-insulated Apartment Buildings, Energy Procedia (2016). DOI: 10.1016/j.egypro.2016.09.177

Related Stories

10 ways to keep your house warm (and save money) this winter

November 22, 2016

In Britain, people typically switch their central heating on in October and use it daily until March or April. This coincides with the clocks going back, the drop in temperature and Winter Fuel Payments – to anyone who ...

Heating apartment houses sustainably

December 14, 2016

For the energy transition to be successful, it will also be important to secure heat supply of the housing stock by sustainable technologies. About half of the apartments in Germany is located in apartment buildings. However, ...

The vents in your office aren't just pumping out air

August 17, 2016

We rely on our HVAC systems to keep us cool when it's hot and warm when it's cold—but that's not all they're doing. Current systems waste huge amounts of energy and hemorrhage money as a result. It's estimated that buildings ...

Recommended for you

Galactic center visualization delivers star power

March 21, 2019

Want to take a trip to the center of the Milky Way? Check out a new immersive, ultra-high-definition visualization. This 360-movie offers an unparalleled opportunity to look around the center of the galaxy, from the vantage ...

Ultra-sharp images make old stars look absolutely marvelous

March 21, 2019

Using high-resolution adaptive optics imaging from the Gemini Observatory, astronomers have uncovered one of the oldest star clusters in the Milky Way Galaxy. The remarkably sharp image looks back into the early history of ...

Physicists reveal why matter dominates universe

March 21, 2019

Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.