Retrofitting Listed Buildings: Measures, Savings and Requirements

Abstract

The paper presents a case study where the energy demand for a listed building constructed in 1900 is reduced. Many older buildings are listed and have restrictions that include the entire building or that include only its exterior. For the building presented, only its exterior facade is listed. The paper demonstrates measures for the improvement of the thermal insulation of the building with solid brick walls. Durable customised measures are shown. The customised measures are required not to change the overall exterior architecture as the building is considered to contribute to the uniqueness of the local urban environment and therefore listed. The reduced energy demand, related to individual measures, is estimated and building physics requirements are addressed together with the economic options for evaluating the profitability. Tightened requirements to the thermal insulation of new buildings and the resulting demand for a reduction of the energy consumption for heating and comfort, in order to re- duce CO2 emissions, mean that existing and especially older buildings are categorised as having a very low thermal stan- dard compared with today's requirements. Therefore, there is an increased interest in improving the thermal insulation standard of many existing and older buildings. However, many older buildings have restrictions that protect the entire building or that protect only its exterior. Therefore custom- ised solutions reducing the energy consumption are needed for these buildings. Moreover, close attention should focus on preventing degradation of the existing construction when the energy needed for heating and thermal comfort of a building decreases, as a result of measures to improve the thermal insulation. Besides lower heating costs and reduced CO2 emissions, the improvements of the standard of insula- tion could contribute to the elimination of other aspects of discomfort. The aim of the paper is to show solutions that improve the thermal insulation standard of a building with a listed exterior facade. The paper includes technical solutions for improving the thermal insulation standard by showing cus- tomised thermal insulation measures of the building enve- lope. It also addresses issues that must be considered in order to prevent moisture-related degradation of the original build- ing. Furthermore, a simple and accurate method for estimat- ing the decreased energy demand after improvements is ap- plied. Finally, the profitability of the measures is evaluated. The paper is based on guidelines on how to improve the thermal insulation of existing buildings and blocks of flats published by the Danish Building Research Institute (1).