Climate & Cities
Retrofit Stalls On The Buildings Nobody Agrees Who Owns
Upgrading a block of flats requires consent from many owners with different finances and time horizons, which is why the hardest retrofits are legal rather than technical.
The technical means of improving an existing building are well understood. The obstacle in most cities is that the building has many owners and no mechanism to make a joint decision.
Fabric work crosses ownership boundaries
Insulation, windows and ventilation sit in the external envelope, which in a divided building is usually common property rather than part of any individual home.
Work to common parts is decided collectively, funded collectively and carried out on a schedule that no single owner controls.
An owner who is ready to act therefore cannot proceed alone, while one who is not can effectively delay everyone else.
The benefit and the bill land on different people
A landlord pays for insulation and a tenant receives the lower bill, which removes the incentive from the party holding the decision.
Owners planning to sell within a few years discount improvements whose payback runs longer than their remaining tenure.
Long-term residents and short-term investors in the same building will rationally reach opposite conclusions about the same proposal.
Decision rules were written for repairs
Most ownership structures set thresholds for spending on maintenance, which is treated as necessary, and higher thresholds for improvement, which is treated as optional.
Energy work often falls into the improvement category, so it needs a larger majority precisely because it is not repairing a defect.
Some jurisdictions have reclassified this work to lower the threshold, which shows that the barrier is a legal definition rather than a physical one.
Partial work can make things worse
Insulating one flat within an uninsulated block moves the dew point and can push condensation into a neighbour's wall or into the junction between them.
Replacing windows without addressing ventilation tightens a home that relied on draughts for air change, and moisture then has nowhere to go.
Whole-building approaches avoid these effects but require exactly the collective decision that the ownership structure makes difficult.
Finance struggles with shared assets
Lending against a single home is routine. Lending to a group of owners for work on a jointly held envelope requires a borrower that may not legally exist.
Where a management company can borrow, repayment runs through service charges, which raises the question of who pays when a flat changes hands mid-term.
Schemes that attach the obligation to the property rather than the person get around this, and they are the ones that have moved retrofit at any scale.
Questions readers ask
Do green roofs save energy?
Modestly, and mostly on poorly insulated buildings. On a well-insulated roof the thermal effect is small. Run-off attenuation is the benefit that reliably justifies them.
Are green roofs maintenance free?
No. They need outlet clearance, occasional weeding and inspection, and they need access to do it. Most failed installations were neglected rather than badly built.
