Project Overview

This project demonstrates how to design and build a PassivHaus as a contemporary English cottage. The client had outgrown their existing bungalow and they required an incredibly low-energy home that would cater for their current needs, whilst also preparing for the family to grow. Tate+Co worked in close collaboration with sustainability experts Etude to design a family home that would have the smallest possible impact on its environment whilst developing a carefully crafted, modern rural vernacular. A simple rectangular form and pitched roof take inspiration from the surrounding cottages and open the ground floor to the beautiful southern views across the fields. It was important to the client that suitable natural materials were used, therefore a carefully selected wood cladding was adopted, not just to clad the walls but also pop-out windows and the roof. Various widths of cladding board wrap the building to create a seamless, crisp finish. The brief was also to integrate state-of-the-art technology, including multi-mode smart lighting, heat recovery units and thermal stores, an air source heat pump and PV panels (soon to be installed). These were all designed holistically following a fabric first approach for the building to have the smallest possible impact on the environment.

The house sits on a quiet single-track country road with uninterrupted views of the surrounding countryside and is oriented along a north/south axis with the key areas opening to the south to flood the rooms with natural light and maximise the views across the fields beyond.

Approaches Used

An innovative split timber frame structure with Warmcel insulation minimises thermal bridging and increases the use of recycled materials in the build. An exposed polished concrete ground floor slab provides thermal mass, flattening out temperature fluctuations. A wood burning stove with back boiler connected to the thermal store allows the client to use coppiced wood from their land to heat the hot water during the winter. This along with an ASHP means that there’s no requirement for a gas or electric boiler. Wiring has been installed to allow the client to connect future PV’s to run the majority of the power in the house, including the ASHP.

Key Sustainability Objectives/ Outcomes

The brief for Kintyre was to create a certified 4-bedroom Passivhaus with low embodied energy.

The U-values are below Passivhaus standards which means no primary heat demand is required for space heating. A high-performance whole house MVHR system provides pre-heated fresh air whilst extracting warm stale air. An ASHP is used as the primary heat source for hot water via a thermal store, with a secondary wood burning stove also connected. The Energy Use Intensity is 20.9kWh/m2/yr. Kintyre runs on 100% renewable energy which has been procured off-site via Ecotricity.

Timber was sourced from responsible British suppliers, and Warmcel insulation was used which is a high-performance insulation sustainably manufactured from recycled newspaper. A new wildflower meadow has been planted along with approximately 120 new trees as part of the client’s desire to sustainably manage their surrounding land and improve the local biodiversity and wildlife.

The dwelling has been certified as a Passivhaus by the Passivhaus Institute in Germany.

Lessons Learnt

During the procurement of Kintyre, Tate & Co held regular workshops and design team meetings to make sure any design revisions did not have an adverse impact on the PHPP. During this process suggestions were made to improve the detailed design to help minimise thermal bridging and help with air tightness. One of the challenges was the timber frame and foundation detailing, this was overcome in conjunction with Etude who helped form the split timber frame structural detail that improved the U-value of the external building fabric.

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