Harefield House

Harefield House was an exemplar use of integrated technologies, energy performance and building management system with its prefabricated timber kit construction.

Receiving Commended in the Alan King Award for Excellence in Architectural Technology at the AT Awards 2017, Chris Game MCIAT of Plaice Design Company Limited explains the project.

Our clients had long held the ambition to build their own bespoke house in the grounds of their existing home, known as Becketts, in the village of Norton, Suffolk. The brief called for the design of a contemporary, sustainable detached four bedroom dwelling to provide approximately 200 sq. m of living accommodation, together with a detached double garage.

The new house has been designed to celebrate ‘approach, entrance and arrival’ which is seen as a critical element in the success and re-development of the site. To achieve this we have orientated the house on a north-south axis to create more defined public and private realms and to maximise winter solar gain. Particular emphasis has been placed on creating strong visual and physical links to the garden spaces, particularly the private front garden with attenuation pond, which will enjoy the south sun, while being screened by trees and hedging.

Architecturally, the house has been designed to be respectful to its surroundings, with careful thought given to massing, form and materials. The mono pitch roofs (with their lower eaves and ridge heights) reinforce this sensitive approach by enabling the property to ‘sit down’ in the landscape when viewed from the street, while creating a more dramatic elevation to the rear.

The home is effectively hidden from view along the street, but glimpse/long views are possible along the new driveway.

The proposed dwelling uses a contemporary vernacular to express each elevation. Each elevation has been designed differently to respond to its immediate context. The mass of the house has been expressed as two wings to create an interesting roof line, one roof perpendicular to the other. Due to the close proximity of the clients existing home, the placement of windows were carefully considered in each elevation, ensuring views to the garden and countryside beyond were framed, forming a connection with the cycles of nature in the surrounding gardens and fields, while avoiding overlooking and privacy concerns.

At the front of the house (south), the entrance has been marked by a modern porch canopy structure extruded from the principle elevation. The line of the porch roof is then extruded across the width of the house to form a wooden pergola to control solar glare into the lounge and snug, which in turn casts shadows/patterns onto the rendered walls to further animate the facade. Timber boarding has been added to the new garage to visually tie both buildings together in a harmonious way.

As part of the design process a number of methods of construction were explored and assessed for their suitability. Ultimately off-site pre-manufactured panels were specified as they appeared to offer the best balance in terms of air tightness, construction time, specification and cost.

The panels were supplied by Svenskhomes, which arrived on site pre-insulated (with U-values of 0.16 W/m2K for walls and 0.13 W/m2K for roofs), with air-tightness and breather membranes fitted and windows and doors installed and sealed, which were then craned into position.

The prefabricated dwelling is highly insulated and air tight. This has resulted in a comfortable environment year round with minimal heating demand during the winter months.

The home uses a number of integrated technologies, each one controlled by the Loxone Building Management System, which allows remote access via any wireless device with the app installed. This level of control has enabled the clients to become proactive and knowledgeable in the performance of their home.

Underfloor heating has been installed to both ground and first floors, generated via an air source heat pump and this is supported by a mechanical ventilation heat recovery system.

A 4 KW PV panel array further adds to the sustainability of the dwelling, with each panel incorporating micro inverters, which gains better yields and allows the client to assess the efficiency of each panel. Any spare electricity from the PV array is automatically diverted to an immerSUN unit to heat the hot water.

All surface water for the property discharges into an attenuation wildlife pond, with run-off via an overflow pipe into the adjacent ditch.

As a machine for living, the dwelling is proving very effective and is exceeding all the modelled data stated in the SAP calculations.

Judges’ comments:

The choice of construction, prefabricated timber kit, is perfect for this type of project, enabling the balance of speed and efficiency coupled with an environment control system that ensures that all building systems work together to keep the comfort level exactly how the client wishes. Excellent detailing and on-site control has enabled the high as-built air-tightness of the overall structure, which contributes to low running costs.

This article was originally published in the AT Autumn issue 123.

--CIAT

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