2021
In this publication, we examined how deep energy renovation of apartment buildings can be circular as well as efficient. Europe needs to renovate existing housing quickly, but that work can create a new environmental burden when it relies on large quantities of new materials that will be hard to recover later. We focused on offsite-prefabricated renovation and asked how the materials, components, connections and structural choices made today can retain their value in future cycles.
We define circular deep renovation as achieving the full energy-performance potential of a building with life-cycle renewable energy, while keeping materials in technical or biological cycles with as little quality loss as possible. This requires more than recycled content. Circularity has to be considered at the material level, the component level and the building-structure level. A material may be recyclable in principle but impossible to recover if it is bonded, covered, inaccessible or placed where it cannot be safely removed.
We used a DRIVE0 assessment method for prefabricated insulation elements. It combines general questions about products with expected service life, material mass per square metre, embodied energy, embodied carbon, and the share of new, reused and recycled material. We also looked at design for disassembly: connection type and accessibility, crossings between systems, containment and material choice. These details make future recovery a design decision instead of a vague promise.
The practical case was a three-storey Estonian apartment block with 24 homes, built in 1986 and renovated with prefabricated timber-frame insulation elements. We considered options such as finger-jointed timber, recycled glass or cellulose insulation, biobased boarding, recycled textile materials and recovery of existing elements. Every circular option still had to meet moisture, fire, durability and thermal-performance requirements.
The window-glass analysis made the opportunity clear: under favourable conditions, a new circular product could achieve a thermal transmittance more than three times lower than the original glass. Circularity and energy performance do not have to compete. But reuse, recyclability and prefabrication do introduce design challenges. Our conclusion is that successful circular renovation combines appropriate materials with reversible connections, careful placement and realistic plans for disassembly—improving comfort now without making tomorrow’s waste problem worse.