Westmorland Home: High-Performance Family Living in Christchurch

Architect: Vila.nz

Category: Residential / New Builds

Overview

The Westmorland Home is a thoughtfully designed new build by Vila.nz, conceived with flexibility at its core. The design anticipates the evolving needs of family life, allowing for multiple uses and changes over time as the household grows and requirements shift.

The starting point was the site itself. A generous section with excellent level access, unobstructed north-facing orientation and expansive views over a neighbouring reserve provided the foundation for every design decision. Because the reserve ensures those views can never be built out, all bedrooms and living areas enjoy consistent exposure to the northern sun. Equal attention was given to the orientation of children's bedrooms as to the master bedroom, reflecting a design philosophy centred on comfort for the whole family.

Performance and Durability

Performance was a primary consideration from the outset. Drawing on extensive building science knowledge gained overseas, Vila.nz looked beyond New Zealand's code-minimum standards and moved away from conventional timber framing methods that have remained largely unchanged for over a century.

The construction system selected is a high-performance, factory-manufactured structural insulated panel, known as SIP. This particular system is the same one that has proven most successful across North America, Europe and Japan, and has been tested and CodeMark certified for compliance with the New Zealand Building Code.

Internal moisture control was equally important. Well-insulated homes that lack airtightness can suffer serious durability issues, as vapour entering the wall structure risks causing rot in structural timber and is readily absorbed by standard glass wool insulation, which sags over time and creates uninsulated gaps within the wall cavity.

To address this, the walls and roof are completely thermally broken and super-insulated, achieving the following R-values:

Walls: R4.3

Roof: R7.2

The building envelope is also highly airtight, providing resilience against the strong winds the site can occasionally experience.

Foundation and Heating

The foundation is a concrete slab with insulation laid beneath it and a thermally broken concrete edge to eliminate cold bridging. Hydronic in-slab heating has been installed throughout, with water heated by a European air-to-water heat pump that simultaneously serves both domestic hot water and the in-slab circuit.

Unlike conventional heat pumps, radiant underfloor heating does not rely on moving air to warm a space. Instead, it radiates heat upward from the floor in a manner similar to the sun, producing the well-established "warm feet, cool head" effect that is widely regarded as the most comfortable form of heating. Combined with the exceptional level of insulation throughout the building, it also proves to be one of the most economical heating solutions available, distributing warmth evenly to every room in the house.

Passive Solar Design

Solar gain through the windows is absorbed by the exposed polished concrete slab, which passively contributes to heating the domestic hot water supply. The hydronic system circulates warmed water through the slab, redistributing heat from sun-exposed areas to less exposed parts of the floor, equalising temperature throughout the home.

The roof on the northern side has been designed with a generous overhang that provides complete shade from the high summer sun while still allowing the lower winter sun to reach deep into every room. Natural ventilation is achieved through passive convection: opening a narrow window in the ground floor office and a high window in the upper floor dining room creates a convection current that, on most summer days, provides sufficient fresh air circulation without any mechanical assistance.

A Home Built to Last

The Westmorland Home demonstrates what is achievable when building science, site analysis and considered design work together. The result is a home that is comfortable in every season, efficient to run, durable by construction and responsive to the life of the family within it.

Looking for the most efficient hydronic heating solution for a new build? You can refer to this page.