Introduction

The behaviour of European Union consumers is likely to evolve in the direction of more air conditioning. In order to answer to environmental rules, new high performance appliances will appear on the market with for example infra-red sensors to detect human presence, or remote control thanks to internet. The future air conditioning will answer to the more and more accurate human requirement in comfort, quietness, hygiene and health.

However, one must say that the effort of architects towards a bioclimatic architecture, taking advantage of natural heat in winter and natural cool in summer, can be very effective in some climates and should be taken into account in a building project

The choice of the equipment will strongly depend on the customer need, space available, budget and frequency of use.

But the installation of an air conditioning system mustn't be the first solution to provide "summer-comfort"; indeed, the characteristics of a building - for example its inertia or its exposure - take important places when one considers the comfort aspect.

It 's the reason why the possible actions on the structure of a building must be considered before the installation of an air-conditioning system.

To conclude, the choice of an air conditioning system will vary if it equips a new building or a renovated one.

Building under construction

In a building the "winter-comfort" is easily achieved thanks to a central heating system but the "summer-comfort" is more difficult to reach.

On one hand natural lighting should be preferred because it reduces the electrical bill, but on the other hand, the excessive outside supplies of hot air and solar radiation must be controlled.

It's the reason why it's good to equip the building with absorbent glazing, moveable outside protections, architectural masks or fix screen. These measures must be adjusted depending on the exposure of the walls (in summer, a southern exposure receives less solar radiation than a building with western or eastern exposures).

Moreover a building must have a strong inertia in order to make a diurnal or nocturnal ventilation useful.

The free-cooling technique must be considered as an interesting solution when the building has a high internal load (then the outside ambient is lower than the inside temperature and the air can be ventilated without being cooled).

Finally, the building structure should include patios and open-plan offices with vegetation and ornamental lake to reduce the outside temperature (to protect the building from the sun in summer, trees with deciduous leafs are very useful). Reflecting colours should be used for the external walls.

These different actions increase the comfort of the occupants, decrease the cooling power installed and so allow energy savings. However, these measures can be not sufficient to maintain a comfortable temperature in summer. In this case the installation of an air conditioning system seems to be necessary.

Buildings under renovation

Two situations are conceivable: the building is already equipped with an air-conditioning system, or the building is not air-conditioned. The two different situations will be detailed distinctly, but before installing or renovating an air-conditioning system, one must act on the general architecture of a building to decrease the cooling power.

In the case of a building under renovation, its global architecture can't be changed, but it can be improved.

In the case of a building under renovation, its global architecture can't be changed, but it can be improved.

The excessive outside supplies of hot air and solar radiation must be controlled.

It's the reason why it's good to equip the building with absorbent glazing, moving outside protections, architectural masks or fix screen.

These measures must be adjusted depending on the exposure of the walls (in summer, a southern exposure receives less solar radiation than a building with western or eastern exposure).

Open-plan offices with vegetation and ornamental lake should be installed to reduce the outside temperature (to protect the building from the sun in summer, trees with deciduous leafs are very useful). Reflecting colours should be used for the external walls.

Finally, a diurnal or a nocturnal ventilation can be used to limit the ambient temperature.

These different actions increase the comfort of the occupants, decrease the cooling power installed and so allow energy savings.