Limit Demand

Waterfront Vancouver © Fairmont Hotels & Resorts

Improve outer building shell / reduce transmission loss

At the level of individual buildings, optimising windows, sun blinds, daylight penetration and wall, roof and floor insulation are all factors that help to reduce the amount of energy used for heating and cooling. Facade and roof vegetation can reduce energy demand, as the part of the building behind or below the vegetation remains cooler in summer. In winter loss through transmittance is limited here due to the extra layer of insulation.

For insulation using green facades, see Green facades.

Insulation using green roofs: see Green roofs.

Improve outer building shell by insulation - Source: Atelier GROENBLAUW

Reducing the need for cooling

In the context of climate change and global warming, sun blinds are an option that deserves more attention. Better insulation means that houses are being air conditioned more and more frequently. In the Dutch climate, if the architectural design is good and if proper exterior sun blinds are used, air conditioning is unnecessary, and should in fact be avoided.

The most important principle in air conditioning buildings is to create architectural designs that require very little, if any, air conditioning. A great deal still has to be done here: new buildings that are properly insulated but lack exterior sun blinds often become too hot. The increasing use of air conditioning units, which use a lot of energy, in residential construction shows that this problem needs to be addressed to limit the proliferation of those units. Exterior blinds combined with a design that is geared towards the local climate present a reasonable alternative, if necessary linked to a thermal activation system for building elements combined with a heat pump. Besides heat pumps, co-generation systems can also be used for cooling purposes in the summer. Solar energy is another possible means of powering air conditioning: it offers the advantage that energy for air conditioning is available when most needed. However, this is an expensive solution, since investments are needed not only for the air conditioning units but also for the solar energy.

Vegetation can be used as a sun shade; deciduous plants provide shade in summer while letting warming sunshine through in winter.

Reducing the need for cooling - Source: atelier GROENBLAUW

In the context of climate change and the heating up of our cities, neighbourhood green and evaporation from vegetation and thus cooling is of great value for the microclimate and quality of life in an area.

City and neighbourhood parks have a tempering effect on the temperature in adjacent neighbourhoods with a reach equal to the radius of the park. Green zones in cities which connect to outer green areas also provide urban ventilation. All these temperature lowering measures reduce the need for cooling and improve the urban climate (see Heat).

Building element activation

The thermal activation of building elements, ceilings, floors and walls for heating and cooling purposes is used in combination with a geothermal heat pump. This is an efficient technique in situations where cooling is necessary.

Underfloor heating pipes © H. Raab, Wikipedia, June 2006

Efficient and healthy ventilation

In recent years, efficient and proper ventilation in homes has been the focus of much attention. Users generally prefer a combination of mechanical extraction and natural inflow. Hybrid systems are a possible solution for passive houses and zero-energy houses.

The Fraunhofer Institute’s Energetische Quartiersplanung presents the conclusion that the forced ventilation concepts that have been becoming more and more common in residential construction in recent years as a means to save energy generally do not yield the presumed levels of savings. The reason is the lower efficiency of air-based heating concepts, as a result of the unavoidable loss of pressure in the distribution system and the higher demand for energy for transporting the energy through the building. The larger the building is or the higher the demand for ventilation is, the less efficient the system becomes.

Combined with the psychological resistance among users against forced ventilation systems, this has led to the use of hybrid ventilation systems, in which the balanced ventilation is switched on only on extreme days when it makes sense energy-wise. On other days, the buildings are ventilated naturally.

Ventilation systems that are controlled according to use or by pollution meters are used to make the ventilation more efficient Erhorn-Kluttig et al., 2011.

Using underground pipes for ventilation allows the ventilation air to be preheated or cooled.

Investment costs related to thermal conductivity of roof, façade, basement and windows. © Fraunhofer Institute
Gross extra costs for low energy buildings (apartment buildings) based on the buiding cost index of the German ‘Architektenkammer’ and an evaluated demonstration project of the Fraunhofer Institute for Building Physics. © Erhorn-Kluttig et al., 2011
Gross extra building costs related to heating energy demand based on evaluations by the Fraunhofer Institute for Building Physics © Erhorn-Kluttig et al., 2011

Efficient appliances and lighting

Using energy-efficient appliances such as refrigerators and washing machines, optimising daylight penetration and reducing standby use of computers and similar machines can help limit the amounts of electricity used.

A significant amount of energy can be saved by using LED lighting outdoors and for lighting that remains switched on for hours at a time. Besides LED lighting, energy-saving lighting can of course also be used for lights that spend a great deal of time on in homes. Optimising the lighting can offer significant yields; for example, in recent years primarily general lighting has been replaced by workspace lighting in offices. Offices are now also using motion sensors and daylight sensors. Daylight penetration, sun blinds, light conducting systems, the depth of spaces and the colours of surfaces are all factors that can be optimised. Erhorn-Kluttig et al., 2011

Smart meters and operational optimization

Smart meters with which the amounts used are directly visible have been developed for homes. In most households they lead to 5-10% savings.

It takes at least a year to optimise the settings for energy, cooling and lighting systems in offices and similar buildings. This optimisation is particularly important in buildings with energy-efficient concepts to achieve the goals and perhaps draw lessons from what components do and do not function optimally.


Of course it is also very important to properly educate people about buying and using energy-efficient appliances. In offices, energy-efficient ICT equipment can reduce the amount of energy used by up to 50%. Standby modes with automatic switch-off are important.