Energy Optimization in Residential Buildings

The importance of local and global issues related to the production of energy makes efficient measures to influence energy consumption a priority. Private households account for some 23% of the total energy turnover of the OECD countries; of this, 68% in apartment housing and 78.6% in single-family homes are used for heating purposes. Although resident behaviour has a considerable influence on this aspect, it is taken into account only as a vaguely estimated factor in conventional analyses.

This research project investigated measures for energy optimisation in social housing, using as a model the "Solar Housing Project Plabutsch – Graz, Styria". Although variants of geographical orientation and technological measures were also analysed, the main focus was to investigate the influence of resident behaviour, using dynamic simulations. Resident behaviour was investigated with regard to ventilation, temperature, heating, shading/insulation through blinds, and variants of occupancy (sources of heat).

The exclusively southern orientation of the building proves an optimal measure to reduce heating energy needs, though the external blinds are essential to avoid overheating. Among the technological measures simulated, only a heat recovery system appears worthwhile. In other words, heating energy needs can be lowered considerably already during the planning stage without additional technological measures, but simply by making the best possible use of the site conditions.

Evaluation of the dynamic simulations shows that resident behaviour can raise or lower heating energy needs by as much as 70%. As regards ventilation, shock airing should be preferred, to allow only a minimum of the heat stored within the building to escape. Room temperature is an essential factor for heating energy needs; a temperature increase e.g. by 1°C at a higher temperature level requires considerably more additional energy than the same increase at a lower temperature level. As regards heating, operation of the heating system from 6 a.m. to 10 p.m. is recommended as the most efficient option. Improved insulation quality and separate winter and summer regulation of the blinds can considerably reduce overheating in summer and heat loss in winter. Full or half occupancy of the apartments during the day reduces heating energy needs to levels close to those of passive solar housing.

The results described in the present doctoral thesis will serve as the basis for a research project which provides for the empirical measurement and analysis of the data simulated in this paper. This thesis therefore makes an important contribution not only to greater precision in the prediction of energy needs, but also to the analysis of actual energy consumption.