Woodside: A Whole-House Retrofit in the Forest of Dean

A 3D perspective of Woodside showing the different wall types incorporated into the whole-house retrofit

Improving the energy performance of an existing house means working with what is already there. Walls may have been built at different times, external finishes may need to be retained, and the space available for insulation can vary from one room to another. Some aspects of the construction may also remain uncertain until work begins.

Our Woodside project in the Forest of Dean responds to these challenges through a whole-house retrofit strategy. The proposals bring together upgrades to the walls, roof and floors, using thermal modelling to inform the design and detailed construction drawings to resolve how the improvements fit together.

Working with Varied Construction

Applying one insulation detail throughout a house can overlook important differences in construction, appearance and available space. We developed several wall strategies, combining internal and external insulation, including woodfibre materials, with lime finishes and timber cladding where appropriate.

The choice between insulating internally or externally has consequences beyond energy performance. Internal insulation affects room dimensions and the connections around floors, partitions and windows. External insulation changes the relationship between the wall face, roof edges and openings. Each approach needed to be considered in its particular location.

Several wall build-ups combining internal and external insulation to suit the home’s varied existing construction.

Using PHPP to Inform the Design

We used the Passive House Planning Package (PHPP) to assess the proposed thermal upgrades within a coordinated building model. This informed insulation levels, construction build-ups and performance targets across the house. Modelling allowed us to consider how the walls, roof and floors contribute to the overall strategy, rather than specifying individual upgrades in isolation. The calculations developed alongside the architectural and technical design, bringing performance ambitions into discussion with the practical constraints of the building.

Making the Connections Work

Insulation continuity requires careful attention where walls meet floors and roofs, and around windows and doors. The technical design focused on reducing interruptions in the insulation and addressing potential thermal bridges—places where heat can escape more readily through the construction. Connections between areas using different insulation strategies also required coordination. These junction details translate the energy strategy into information for construction, showing how the separate improvements form a connected thermal envelope.

Retrofit starts with some unknowns: the proposed floor upgrade will need to be reviewed once the existing construction is exposed.

Working with What We Find

Detailed proposals still depend on understanding the building beneath its finishes. The existing floor construction remains uncertain, and the proposed upgrade may not be achievable if the available depth or conditions differ from our assumptions. Opening up will establish what is possible and whether an alternative approach is needed.

Retrofit therefore involves both careful preparation and a willingness to adapt. The aim is to carry the energy strategy through those decisions, reviewing the details as more becomes known about the house.

For Woodside, success will mean turning that strategy into practical improvements that make the home warmer and reduce its heating needs, while working carefully with the building we find.

More information can be found on the project page.