Retrofit Projects& case studies

We helped create a PHPP energy model for a new build Passivhaus according to an architect’s drawings – this included liaising with the Passivhaus certifier Etude to get the model to a certain stage.

An airtightness test was carried out to highlight air leakage areas, which was followed by a recommended list of improvements. There were some issues related to the MVHR not functioning and these were examined and referred back to the original installer. Access to the unit was also not ideal (via a non-boarded cold loft) and the ducts were also not well insulated, in some places having no insulation. In addition, the MVHR air intake was fairly close to the boiler flue, which had not been considered in the design. Overall this was another case study in how not to design and install ventilation systems!

This site consultation was to discuss retrofit options with a client who was planning to do a lot of the retrofit work themselves. Various options were discussed, after which the clients were referred for further discussion with Greengauge Building Energy Consultants regarding the early cavity wall in relation to internal insulation options. We also convinced the client to attend the Passivhaus Tradesperson training which provided a good foundation for understanding about fabric-first construction.

An airtightness test was carried out to highlight air leakage areas, which was followed by a recommended list of improvements. The MVHR ventilation system also had several significant performance issues which had to be resolved – one of the main problems was that the filters had not been changed in years (which highlights the need for proper handover to homeowners for the running and maintenance of these systems). The access to the unit had also not been considered by the installers – it was at the far end of the cold loft that had not been boarded out. The ducts were also not well insulated, with tumble dryer duct installed on one of the ports. This was all a classic case of bad design, installation and handover.

A whole house retrofit plan was created based on PHPP and thermal bridge modelling, followed by MVHR design and full costing / BoQ. A Karsten tube brick absorptivity test was also conducted on external walls on which internal wall insulation was planned, which provided data for a WUFI hygrothermal model (run by Greengauge Building Energy Consultants) in order to decide what a safe level of insulation would be from a moisture risk point of view, as well as what type the airtightness layer would be best.

An airtightness test was carried out together with the client who wanted to know what to address in terms of air leakage, followed by a recommended list of improvements. The main leakage area was the unplastered wall within the floor void that even caused carpets to balloon up during the test!

Created a whole house retrofit plan informed through PHPP and thermal bridge modelling, followed by MVHR design and a full costing / BoQ.

This was the Zetland Road EnerPHit Plus project where we were involved in some aspects of the building work. This involved troubleshooting airtightness issues in the roof (the contractors who had installed the membrane had made multiple holes in it that were covered up by service void battens), physically installing the wood fibre on the front bay walls (a complicated task given the odd-shaped walls and numerous floor void areas) and blowing in cellulose insulation behind this wood fibre. In addition we helped check the PHPP model and carry out thermal bridge modelling for some junctions. This project has been written about by the Passivhaus Trust here.

A whole house retrofit plan was created for this dormer bungalow based on PHPP analysis and thermal bridge modelling. The house had numerous challenges including a wide variety of wall types (solid, filled cavity, unfilled cavity, timber frame), a challenging form factor and a lot of air leakage (18.9 ACH).

After water was found dripping back through recessed lights in a newly constructed flat roof that had formed part of a loft conversion, a contractor asked us for help to diagnose the situation – they had not found any issue with water ingress from outside and were baffled as to what was going on.

The issue was actually related to an inadequate airtightness barrier on the warm side of the insulation which had caused serious mould and condensation issues in the roof space within two months of completion – condensation had formed on the roof deck, which dripped back down onto the vapour-closed insulation before spilling through the recessed light fittings once the puddles got large enough! This was as much the fault of the architect whose details were completely inadequate in terms of detailing for airtightness (it continues to be a very common problem), and yet it was the contractor who had to bear the brunt of responsibility to sort it out. Remediation involved removing the ceiling plasterboard, installing airtight downlight boxes over the recessed lights (we had to also insulate those boxes ourselves first as they were taller than the insulation layer), before adding an airtight membrane that was taped to these downlight boxes and all perimeters (including to the top rail of a stud wall which wasn’t a perfect solution), followed by plasterboard. We helped to carry out and supervise these remediation works.

Following PHPP analysis, thermal bridge modelling and a retrofit plan that was carried out in 2016, some work has now been completed including insulation of the suspended wooden floors.

This was a phased retrofit that has been mainly carried out by the homeowners themselves. The house had filled cavity walls and some floor insulation, but was uncomfortable to live in and had a space heating demand of 200 kWh/m².yr. A retrofit plan was made based on PHPP along with thermal bridge modelling for the junctions, and also we carried out a detailed BoQ / costing.

Once the work began, we have provided support to the clients during their retrofit journey, making site visits when requested to brainstorm particular problems. The retrofit is now complete, which involved internal wall insulation using wood fibre followed by an airtightness membrane and service void, insulating the floor of a previously converted garage, new triple-glazed windows and doors, an MVHR ventilation system, a revamp of the solar hot water system along with a new heat pump, and an existing conservatory that was converted to an extension. Based on the final air test, the space heating demand is now around 69 kWh/m².yr, although it has probably reduced further based on repairs done to the airtightness layer following the final air test. The compromise in this project was to leave the floor intact, which at the outset had a minimal amont of EPS insulation under it, but it was decided to leave it because of the extra disruption that would have been caused to relay it. This project has been written about by the Green Building Store here: https://www.21degrees.com/case-studies/room-by-room-diy-retrofit/