Denmark has an historically low real consumption of energy for heating, which has been ascertained by researchers at Aarhus University based on extensive data analysis of the district heating consumption in single-family houses.

“We can see a clear correlation between the age of the buildings and the actual energy consumption, with a very significant decline starting with houses built in the 1950s. This means that we now have an empirical overview that makes it possible to document the impact of historical energy-saving requirements in the building regulations,” says Associate Professor Steffen Petersen, Department of Engineering, Aarhus University.

The researchers closely studied district heating consumption in the last three years for a total of 28,000 single-family houses built in the period from 1900 and up to 2012.

Using information from the national Building and Housing Register (BBR) and smart meter data for the individual households, they succeeded in showing average consumption in time-related development.

It has not previously been possible to document the real effect of legislative energy requirements for houses.

Energy requirements in the building regulations do work
The Aarhus University researchers worked closely on the extensive data analysis with AffaldVarme Aarhus (Waste and District Heating Aarhus) – one of Denmark’s largest district heating providers.

Based on the results, they can conclude that the increased energy requirements in the 2006 building regulations have had a particularly positive effect.

During the period from 2006 to 2011 alone, heating consumption in single-family houses fell by 25 per cent, which corresponds to the political ambition of the specific requirements.

“Our study provides solid documentation for the increased energy requirements having an impact on the actual household energy consumption. It’s clearly shown in the data that one of the most ambitious initiatives ever undertaken to tighten energy requirements in the building industry has had the desired relative effect on the actual energy consumption of single-family houses,” says Martin Kristensen, a PhD student at the Department of Engineering, Aarhus University.

In research circles, the effect of the increased energy requirements in the building regulations has been a topic of great discussion for a number of years.

In the video below (in Danish), you can see the researchers’ data visualisation of the historical development in heat consumption.

(Video: PhD student Martin Kristensen, Department of Engineering, Aarhus University).

Considerable difference in houses with the same energy label
The comprehensive analysis of district heating data shows that the average energy consumption for heating homes depends on the specific energy requirements in the year of construction.

The researchers can nevertheless ascertain that there is significant diversion in each construction year.

“When we consider the average district heating consumption in the building stock, it appears as a clear function of the year of construction. If we take a slightly more detailed approach, however, we can see that there are very large variations in the energy consumption in otherwise comparable single-family houses,” says Associate Professor Petersen.

Part of the explanation of this can be variations in the number of household occupants and different preferences regarding comfortable room temperatures.

According to Associate Professor Petersen, however, high energy consumption can also be due to faults and defects in the construction work.

“In newer houses, energy consumption at the high end of the scale can possibly be caused by an insufficient building envelope, poorly regulated ventilation and heating systems – and even shoddy work and negligence,” he says.

The difference between the estimated and the measured energy consumption is most pronounced in newer single-family houses, and this gives rise to checking the existing calculation methods in the building trade.

“It’s a big problem. We have to take a closer look at the methods and standards used by engineers when they’re calculating a household’s energy consumption while the building is still on the drawing board. It should be such that both homeowners and utility companies experience that theory matches reality,” says Associate Professor Petersen.

Minute-by-minute data can reveal energy traps
In the time ahead, the researchers will increase their collaboration with AffaldVarme Aarhus to identify the exact causes of the large diversion in the household energy consumption.

This will also provide new knowledge about opportunities for optimising district heating operations.

“We’re in the process of analysing household energy consumption for heating on a weekly, hourly and minute-by-minute basis, and then it’s likely that we can point out how we can optimise district heating operations and the pipeline network. We’ll also take a closer look at how we can make the energy calculations in the current building regulations more accurate for the actual operations. Our aim is to create an evidence-based foundation for decisions about future investments,” says Business Developer Adam Brun, AffaldVarme Aarhus.

About the project

The research into the actual energy consumption in single-family houses is part of READY – one of Europe’s most comprehensive energy research projects.

For more information, please contact

Associate Professor Steffen Petersen
Department of Engineering
Aarhus University

PhD student Martin Kristensen
Department of Engineering
Aarhus University

Business Developer Adam Brun
AffaldVarme Aarhus
adbr@aarhus.dk