Heat loss in buildings

SDG Ensure access to affordable, reliable, sustainable and modern energy for all

The level of comfort inside a building depends upon the season, time of day and whether the room is being heated or cooled; it also depends upon the level of activity such as working during the day or sleeping at night. In the home the largest amount of energy is used for space heating and it is important to understand the ways in which heat can flow in order to reduce our energy consumption and use energy more efficiently.

Heat flow

Heat is a form of energy which flows from a hotter to a colder source. Solar radiance is the most important factor in determining heat flow; in summer heat is likely to flow into a building whilst during the winter the flow is reversed. Northern Europe has long winters and short summers whereas the length of the seasons is reversed in southern Europe.

The level of comfort inside a building depends upon the season, time of day and whether the room is being heated or cooled; it also depends upon the level of activity such as working during the day or sleeping at night. In the home the largest amount of energy is used for space heating and it is important to understand the ways in which heat can flow in order to reduce our energy consumption and use energy more efficiently.

Heat transfer

Heat energy can be transferred from a hot to a colder object in three ways -

• Conduction where the heat is physically transferred across a like a wall or window
• Convection in which the heat is circulated away from the heat source by moving air
• Radiation in which heat is transferred by heat waves, the sun being the ultimate radiation source

These heat transfer processes are all dependent upon the difference in temperature between the hot and cold source; the greater the temperature difference the faster the heat transfer

Adding insulation

The average life time of a dwelling in the EU is now more than 100 years. Over the years the building standards have increased in all countries so that the older the dwelling, the poorer is the insulation standard. Increasing the level of insulation to that closer to today’s standards will improve the fabric of the dwelling, extend its life and reduce any condensation that might be present. In this way, savings can be made in terms of energy, money and the environment. A grant may be available to insulate your home so it is worth checking with your local energy advice centre or utility.

As heating our homes in winter is the biggest consumer of energy in middle and northern Europe, it is essential to insulate our buildings in order to reduce the heat loss and thereby the energy demand.