Portfolio decarbonisation.
Carry thousands of homes and the question is never one building. We archetype the stock, prioritise by carbon, cost and need, and set a phased, funded retrofit strategy to net zero. Then we deliver it, EnerPHit at scale, on the council Pathfinder programmes.
What portfolio decarbonisation delivers.
What it isA local authority or housing association carries decarbonisation across a whole portfolio, not a single project. Under the Ireland Climate Action Plan public bodies must cut energy and carbon, reach a minimum BER, and chart a route to net zero by 2050. In England, Awaab’s Law puts hard deadlines on damp and mould, and EPC minimums set a legal floor on lettable stock. Met one home at a time, those duties are unaffordable and slow. Met as a stock, they become a plan.
We archetype the stock into a handful of repeating building types, survey and benchmark them, then prioritise by carbon, cost and need. From that we set a phased pathway against carbon, BER, EPC and cost, and where the fabric demands it we take homes to the EnerPHit standard, the Passivhaus (Passive House) retrofit standard, in one pass. It is the method we run on the council Pathfinder programmes. Because we are Design Team Lead on those programmes, we deliver the pathway as well as write it. The same team leads the deep retrofits that prove it.
Carbon and BER under the Climate Action Plan. Damp and mould duties under Awaab’s Law. EPC uplift on lettable homes. A portfolio pathway folds all three into one prioritisation, so the worst homes are not stranded behind the cheap-carbon work.
A stock archetype model, a phased and costed retrofit roadmap, and a business case a board can fund. Each phase carries its own carbon, BER and cost targets, with whole-life carbon counted and hygrothermal risk checked before a home is signed off.
Six steps from a stock list to a funded plan.
Thousands of homes, no plan, a 2050 deadline and a damp-and-mould duty that does not wait. The way out is not more surveys. It is a fixed sequence that turns the whole stock into one fundable retrofit programme. We run it the same way every time.
- 01 Archetype
Group the stock into a handful of repeating building types. A few dozen archetypes stand in for thousands of homes, so the model is built once and scaled, not redrawn door by door.
- 02 Survey
Survey a representative sample of each archetype and benchmark the rest: fabric, services, BER or EPC, condition, fuel use and the damp and mould flags that carry a legal deadline.
- 03 Prioritise
Rank every home by carbon, cost and need. The worst-performing fabric and the cheapest carbon rise to the top together, so health risk and target are tackled in the same phase.
- 04 Cost
Cost each intervention against the archetype model, from light-touch fabric measures to full EnerPHit deep retrofit, with carbon saved per pound or euro on every line.
- 05 Phase
Sequence the work into phases mapped to the Climate Action Plan milestones and the 2050 target, so the early phases fund and de-risk the later ones rather than chasing every home at once.
- 06 Fund
Build the business case a board can approve, with public funding and grant lines matched to each phase. The plan arrives costed, sequenced and ready to draw down.
The council Pathfinder programmes.
Proof on the groundMosart is Design Team Lead on three council Pathfinder programmes, for Leitrim, Galway and Mayo County Councils. They decarbonise civic and community buildings to a minimum BER B and a route to zero by 2050, the same sequence we bring to a housing portfolio: archetype, prioritise, phase, then lead the deep EnerPHit retrofit delivery.
Method: how we work.
MethodWe sort the portfolio into repeating building archetypes and build the energy baseline for each: fabric, services, BER or EPC, condition and current fuel use. One archetype model stands in for thousands of homes, so the work scales and every later decision rests on real data, not a guess.
Each archetype is modelled and ranked on three axes: carbon saved, cost per tonne saved, and need, which covers fabric condition, fuel poverty and the damp and mould duty under Awaab’s Law. The money goes where it works hardest, the worst homes are not left to fail, and the carbon target stays reachable.
We sequence the work into phases, each with its own carbon, BER, EPC and cost targets, so each phase pays toward and de-risks the next. The pathway maps to the Climate Action Plan milestones and the 2050 net zero target, giving you a year-on-year line to report against.
We produce the business case a board can approve, with the numbers behind every phase and the funding routes set out. As Design Team Lead we then lead delivery, taking the priority homes through design, procurement and EnerPHit deep retrofit so the targets in the strategy are verified on site, not just on paper.
Common questions.
FAQWhat is portfolio decarbonisation, and how is it different from retrofitting one building?
Portfolio decarbonisation treats thousands of homes as a single stock to be taken to net zero, not a queue of one-off projects. The method is fixed: archetype the stock into repeating building types, survey and benchmark them, prioritise by carbon, cost and need, cost the work, phase it, then secure the funding. The output is a housing stock decarbonisation plan a board can fund and report against. A single deep retrofit fixes one home. A portfolio pathway tells a local authority or housing association which homes to fix first, to what standard, and how the early phases pay for the later ones.
How do you prioritise which homes to retrofit first across a whole stock?
We rank every archetype on three things. Carbon, so the pathway reaches the net zero portfolio target rather than picking off easy wins. Cost, measured as carbon saved per pound or euro, so the budget goes where it works hardest. Need, which covers fabric condition, fuel poverty, and the legal exposure that drives a landlord: damp and mould duties under Awaab’s Law, and BER or EPC minimums. The result is a phased retrofit strategy where the worst homes and the cheapest carbon are tackled first, and each phase de-risks the next.
Does the pathway address damp, mould and BER or EPC compliance?
Yes, because those are the duties social landlords are judged on. Awaab’s Law gives social housing providers fixed deadlines to act on damp and mould. BER and EPC uplift is a legal floor on lettable stock, not an aspiration. A portfolio plan folds those obligations into the same prioritisation as carbon and cost, so homes that fail on health risk or rating are not stranded behind the cheap-carbon work. Where a home needs deep retrofit we take it to the EnerPHit standard, which fixes the fabric, the ventilation and the damp risk in one pass rather than papering over mould that returns the next winter.
Can Mosart deliver the retrofits as well as plan them?
Yes. A strategy is only worth the paper unless it can be built, and we are Design Team Lead on the Leitrim, Galway and Mayo County Council Pathfinder programmes. That means we lead the deep-retrofit delivery, not just the planning. The same team that archetypes the stock and sets the pathway takes the priority homes through design, procurement and EnerPHit-standard retrofit, so the carbon, BER and cost targets written into the strategy are the targets verified on site.
Turn your stock into a funded plan.
Tell us the size and shape of your stock. We will archetype it, prioritise by carbon, cost and need, and set a phased pathway a board can fund. Then, as Design Team Lead, we deliver the deep retrofits that prove it.