Life-cycle assessment of transformation scenarios of a traditional Danish house

Renovation is usually seen as more environmentally friendly than restoration, but little information can be found in the literature on the subject. The ‘Apprentices’ House’ is a small neglected half-timbered house from 1887 and located on Bornholm, Denmark. To make the house suitable for dwelling again, a restoration or renovation must be carried out. Environmental life-cycle assessment (LCA) was conducted to quantify the environmental impacts pertaining to those transformation scenarios, to identify the most environmentally friendly way to make the building inhabitable again. The influence of relevant parameters on the output results, i.e., the assessment period of the study (50 or 100 years were considered) and the dataset used to estimate building materials lifetimes (two were considered), was also studied. The results show that for most environmental impact categories, restoration performs as good or better than renovation. This conclusion is robust regarding the choice of the assessment period. When changing the material lifetime data, restoration shows similar impacts, but results for renovation show substantial variations. The LCA results were finally
compared with LCAs on new single family residential houses to assess the climate performance of restoring or renovating as an alternative to demolishing the existing house and building a new one. The comparison
indicates that transforming an existing building appears to be preferable to construction of a building and, thus, the most climate-friendly solution.