Retrofit Projects& case studies

Two site visits were undertaken on behalf of Eric Parks from Buckrose Ecological Architects to check build quality and various specific points with a contractor building a Passivhaus Low Energy Building (this is a recognition for those buildings that just miss being a Passivhaus). Being local, we had been asked to visit since the architect was based in Scotland, in order to reduce travel time during the pandemic.

We created a whole house phased retrofit plan using PHPP and thermal bridge modelling. The house had already had some retrofit improvements added over the years, but some had not been installed so well (for example the cavity wall insulation had not been continued on the wall between the house and the garage). The challenge in this case was to see how far we could get to, with the minimum level of disruption. We also located and briefed a couple of suitable contractors and arranged them to meet the clients to take the job forward – in both cases the contractor did not end up visiting, and the clients are still continuing in their search for a contractor who has attention to detail (they seem to be quite rare in the northeast!).

This cold bungalow had unfilled cavity walls, an uninsulated suspended floor and uninsulated bay roof – the only existing insulation was in the loft spaces. A whole house retrofit plan was made using PHPP and thermal bridge modelling, and included plans for an extension on one side. The aim was for a 91% reduction in space heating demand to reach 36 kWh/m².yr.

We were contacted a couple of months prior to work beginning on an extension, where the client wanted us to review the architect’s proposed design for the extension (while also considering possible improvements to the existing house). This involved advising the architect and contractor on suggested changes to the material specification and u-values based on best practice while considering moisture risk, as well as reviewing the junctions using thermal bridge modelling in order to ensure thermal continuity.

We provided specific advice to someone doing a DIY retrofit project. Work included u-value calculations, thermal bridge modelling and checking the MVHR design assumptions.

We created a phased whole house retrofit plan based on a PHPP energy model and thermal bridge modelling, and helped coordinate the MVHR design. This retrofit had challenging ground conditions (high water table in combination with a timber suspended floor), which required bringing in Greengauge Building Energy Consultants to advise a way forward to address this before any internal works would start for the main house.

The kitchen extension, being a different (newer) build type, was retrofitted as phase 1 of the project (in 2021) during which time the moisture issues were investigated further. For this phase, we finalised the window & door schedule with Green Building Store and helped to find a suitable contractor for the work, after which we made site visits during the first retrofit phase. Part of the MVHR ducting and terminals were procured so that these could be installed early on (to connect with the main system later). In addition, the kitchen radiator was replaced with a larger one which was based on a future heat pump specification. The kitchen retrofit involved insulating over an existing slab, internally insulating walls while also filling the cavity, insulating within / under rafters with wood fibre, and ensuring thermal continuity at all junctions.

We created a PHPP energy model for a whole house retrofit which included plans for a new extension. Work included thermal bridge modelling, MVHR ventilation design, full costing / BoQ and help with finding suitable local contractors.

We carried out thermal bridge modelling for balcony junctions and roof planters after the building had been completed, in order to cross-check the condensation risk of what were existing thermal bridges. Normally thermal bridges in new build should be mitigated or eliminated during the design stage – however it seems that architects are still not well versed in thermal bridging, resulting in standard details that are not very efficient thermally.

Ecospheric had requested our help for several different projects – work included site surveys, PHPP design and thermal bridge modelling.

We created a PHPP energy model for a whole house retrofit of a detached house and adjoining barn. The work included thermal bridge modelling of junctions.

We created the PHPP design along with thermal bridge modelling for junctions, coordinated the MVHR ventilation design, liaised with the heat pump designer and located a suitable contractor. The retrofit had its challenges – a few examples were ensuring airtightness continuity over and behind internal stud walls, insulating a stairwell wall with aerogel boards due to a lack of space, and installing Compacfoam retroactively under an existing door threshold to minimise thermal bridging at the threshold. The retrofit was done in one go (rather than in phases), and although we were not involved a lot during the actual construction, the contractor Haus Martins did a superb job. The final construction achieved a space heating demand of 44 kWh/m².yr and we were then brought in for the final air test (with a result of 1.36 ACH) and to apply for AECB Carbonlite Retrofit Standard certification (which ended up being the UK’s first official retrofit certification!).

This was an ongoing voluntary role to help contribute ideas towards the retrofit challenge that Greater Manchester has as part of their 2038 zero carbon city strategy. We managed to get the AECB involved in the overall strategy regarding targets.