A retrospective of 35 years of old dwellings refurbishment to enlighten the future of energy efficiency in buildings: what and who benefits?

Panel: 5. Energy use in buildings: projects, technologies and innovation

This is a peer-reviewed paper.

Authors:
Marie-Hélène Laurent, EDF - R&D Département ENERBAT, France
Benoit ALLIBE, EDF R&D, France
Dominique OSSO, EDF R&D, France
Guillaume BINET, EDF R&D

Abstract

Before the first oil crisis, the majority of European countries new buildings were constructed without any energy efficiency obligation. In those times, space heating accounted for more than 80% of the energy consumption of residential sector. In France, (SH) consumptions in dwellings was rated at 300 kWh/(year.m²), final energy.

40 years later SH is only 60% of total consumption and the unitary SH consumptions has been cut by almost 50%. Unitary efficiency has been sufficiently strong to decrease total SH consumptions despite increases of number and size of dwellings and standards of comfort.

This paper studies the causes of this spectacular increase in energy efficiency: what are the respective responsibilities of demolition, refurbishment of existing housing stock, efficiency of new dwellings and daily behaviour? A particular attention is given to pre 1975 dwelling stock. The pre 1975 French dwelling stock still represents more than 50% of main housing in France but 2/3 of space heating consumptions. Due to slow renewal of the stock, it will constitute almost 40% of main houses by 2050. Understanding the past benefits of retrofitting on this particular stock is important to forecast future consumptions as well as to design future policies.

Our analysis is based on SH energy consumptions time-series from 1975 to 2010 of dwelling’s different vintages and various building census. In our paper, behavioural evolutions are quantified with the calculation of Space Heating Intensity Factors (SHIF), the ratio between observed SH consumptions and EPC (Energy Performance Certificate) normative ones, used in literature and considered as a proxi of households’ behaviour regarding space heating consumptions and thermal comfort. SHIF has been estimated for the pre 1975 dwelling stock by 1975 and by 2006 to determine if the increase of efficiency has been partly transformed in “increased” comfort or not. Quantifications of these 4 main identified drivers (demolition, refurbishment, new dwellings and behaviour) are proposed. Quite surprising results like evolutions of SHIF are discussed.