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 relevant literature on the subject.
The ‘Apprentices’ House’ is a small, neglected, half-timbered house from
1887, located on the island of Bornholm in Denmark. To make the house
suitable for dwelling again, a restoration or renovation must be carried out.
An environmental life-cycle assessment (LCA) was conducted to quantify the
environmental impacts pertaining to those transformation scenarios, so as to
identify the most environmentally friendly way to make the building inhabitable
again. The influence of relevant parameters on the output results, that is,
the assessment period of the study (fifty or one hundred 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 expose substantial variations. The LCA results
were finally compared with LCAs on new single-family residential homes 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
the construction of a building and, thus, the most climate-friendly solution.