Buildings are voracious consumers of energy. Leaving aside all the household appliances and other machines they may contain, to heat or cool them requires the use immense energy resources. The exact amount depends on the building�s orientation, the criteria applied in its design and the materials used.

As early as 1993 a European directive, number 76/93, was introduced to tackle the issue of reducing of CO2 emissions by improving energy efficiency in the building sector. In its article number two it obliged member states to set up various programmes including the energy certification of buildings. Now, nearly ten years on, that certification is close to becoming a reality.

In order to develop a computational tool which would allow us to know the energy parameters of housing, the Institute for Energy Diversification and Saving (IDAE) sought the collaboration of the Sevilla School of Industrial Engineers, which in the year 2000 presented the fruit of their labours: the CEV programme. As the different variables are introduced (orientation of the building, design, shade that other adjacent buildings may cast, the existence of awnings above the windows, type of insulation used, type of heating and cooling system, etc.) the programme delivers a breakdown of the results and suggests where improvements might be made to increase its energy rating.

With this tool any developer or architect can make the appropriate calculations to achieve an energy rating for housing on a scale of 5 to 10, with 10 being the highest score and five being the rating granted to buildings complying with the minimum requirements laid down by the Regulation of Thermal Installations in Buildings (RITE). The software presents its results in terms of equivalent CO2 emissions, as required by Directive 76/93.

The delay of nine years since the directive was first published is due, among other things, to the leeway given to each member state with regard to the scheduling of concrete measures. And, as is generally the case, this has meant that no country has been in too much of a hurry to do anything. And besides it has only been relatively recently that people have started to show any concern for energy issues. The IDAE itself commissioned a sociological study some time ago to find out what interest, if any, house buyers had in matters of energy insulation, and the report confirmed that it was a very minor factor in the house buying process.

The fact is that at this point in time efficiency is not a selling point. The housing builders and developers know this and, for that reason, they make no effort over and above what is strictly compulsory. And why should they when it is the buyer and not the developer who is going to pay the heating or air conditioning costs?

However, the potential for increasing efficiency are enormous and the effect that could have on a house buyer�s pocket are such that if he or she were better informed on the subject, that lack of interest could easily be turned around. According to the IDAE, it's not a matter of demanding that housing has a good energy rating. The important thing is that houses have a rating and that buyers know what it means. When that day arrives, efficiency is bound to become a selling point.

Energy labels for buildings will become obligatory in a very short time, as they have already become in some European countries. The Royal Decree which will make it compulsory for all types of buildings (not only housing) to have an energy rating is scheduled for early 2003. Brussels realised that the Directive 76/93 was not demanding enough for the times we live in and so there is now a proposal for a directive, passed by the European Union energy ministers last December, which will take the issue a stage further. The new directive will oblige all new buildings and some existing ones (those with a usable floor area more than 1,000 square metres which are gong to undergo a major refurbishing) to obtain an energy rating.

The new regulations will demand even more: any person wishing to sell their house will have to provide the buyer with an energy rating obtained within the last five years, so that all the elements in a house which influence its energy performance (including those that may have been added or, conversely, those that may have deteriorated through use) should be taken into account. For this reason every 10 years buildings will have to be re-rated, and the result will have to be posted at the entrance, as set out in the draft directive.

It is clear that these two legislative initiatives will have a radical effect on the hitherto gloomy outlook with regard to buildings� efficiency. Up until now buildings had scarcely been considered as consumers of energy, an energy which for decades has been paid not by the housing�s builders but by its occupants.

DID YOU KNOW...?
- 57% of all the energy which European homes consume goes on heating. While the expenditure on air conditioning in private houses is not significant, the number of buildings equipped with cooling systems is rising continually, and, according to the Green Book Towards a European strategy for the security of energy supply, COM 2000, offices, stores and hotels, for example, currently devote 4% of all the energy they use to this end.�

- The quality of housing from an energy point of view can be improved at a low cost. The Madrid City Hall is constructing three buildings of model housing in which the best criteria of energy efficiency have been applied. In their planning stage two of them obtained ratings of 10 and 9, respectively. It is officially protected housing, part of Spain's social housing programme.