Metering and charging on an individual basis of heating and hot water consumption is at varying levels of development in European countries. The 2012/27/EU Directive on energy efficiency published in 2012 stipulated the compulsory nature of implementing this kind of system across all member states. Despite the 2016 deadline laid down by the directive for the states to transpose the directive into their internal legislation, today "this has not been done here; right now, there is a draft Royal Decree by which the directive will be transposed, but it has yet to be passed," explained Jon Terés, a member of the ENEDI research group at the UPV/EHU's Faculty of Engineering -- Bilbao and one of the authors of this study.

Despite the fact that current legislation does not yet make this compulsory, "an attempt has been made by installation and maintenance companies and even property administrators to encourage individualisation in communities with centralised heating systems, in other words, those in which a heating and domestic hot water system, and cooling, where appropriate, is supplied to more than one end user. That is why there are more and more communities of residents that decide to go ahead with the installation, although the vast majority of buildings with centralised installations built before 1998 still do not have these systems," he said.

The ENEDI research group has conducted a detailed study of the savings to be made through the individualisation of the metering and charging of the heating and water consumed in a block of about 140 flats in Bilbao. As the researcher explained, the aim sought by this study was "to find out how much energy was being saved through this measure in temperate climates. Most of the studies of this type have been carried out in the north of Europe where climate conditions in winter are much harsher. We aimed to see the extent to which the results of these studies could be extrapolated to our climate, where the winters are much milder."

In the study conducted they compared the community's heating oil consumption during the two years prior to the intervention with the consumption over the two years that followed. "The results revealed energy savings in the building studied of up to 20% during the period studied; these percentages of savings are very similar to those seen in publications focussing on the conditions in the north of Europe. What is more, in this particular case study, the payback period on investment would be about 10 years, perfectly manageable for systems of this type," specified Terés.

Greater control of and flexibility in consumption

The main difference resulting from consumption on an individual basis is that it allows greater flexibility in the use of the heating system and the possibility of adjusting it to the needs of each home; and when the users pay on the basis of consumption, they become more aware of their use of heating and domestic hot water. As a general rule, this awareness underpins the reduction in consumption in the homes in the block.

What happens in communities where consumption is not on an individual basis, is that "the residents are often unable to turn the system on and off, and the heating functions on the basis of what the community has agreed, following criteria with respect to the calendar and time of day, irrespective of whether the homes are occupied or not in that period, or the temperature that each user wants to have in his/her home; the scenario emerges of having the windows open in winter and the heating turned on," specified the researcher. Furthermore, the heating cost is shared out on the basis of criteria that have nothing to do with the consumption made, such as the number of square metres of each flat.

In view of the results, Terés believes that this case study constitutes "an interesting starting point for this type of study in temperate climates. Right now, we are working on the study of individual consumption, because there are some residents who save much more than others, and we would have to conduct the same study on a bigger number of blocks of flats and perhaps taking longer periods of time into consideration to be able to extrapolate and draw general conclusions from the results."