Sussex Barn Conversion

The Brief

A converted agricultural building in the South Downs National Park had been transformed into a four-bedroom family home with striking full-height glazed gable ends facing east and west. The views across the valley were the centrepiece of the design — and by summer, the source of the house’s greatest discomfort. Both gables created intense solar heat gain that made the central living space unusable on warm days, and the bedrooms above insufferably hot at night.

The client’s architect had specified TM59 dynamic thermal modelling during the planning application. The simulation confirmed that without external shading, the building would fail Part O’s operative temperature criterion on 18 days per year in the 2080 weather file, rising to 31 days in worst-case scenarios.

Our Approach

The east gable faces the morning sun from early spring through late autumn. For this elevation, we specified motorised external roller screens in a 3% openness charcoal mesh fabric, operating via Somfy io-homecontrol sun sensors programmed to deploy at 300W/m² solar intensity. The screens retract when solar intensity drops below threshold or wind speed exceeds 38km/h. When closed, the fabric’s g-value of 0.12 reduces solar heat gain by over 85% compared to the unscreened glazing alone.

The west gable presented a different challenge: low-angle afternoon sun penetrating beneath any horizontal overhang. We worked with the architect to specify adjustable aluminium louvre shutters, mounted externally on a proprietary track system. The louvres angle automatically to block direct solar radiation while preserving the view of the valley and maintaining cross-ventilation — an important consideration in a barn with limited mechanical cooling.

Technical Specification

Both shading systems are integrated into the client’s Apple HomeKit smart home installation, with the following automation logic: morning scene deploys east screens at 07:30 from April to September; afternoon scene deploys west louvres at 13:00; evening scene retracts all shading at sunset. Manual override is available via iPhone, iPad, and physical wall switches in the kitchen and master bedroom.

The roller screen cassettes are powder-coated in RAL 7016 Anthracite Grey, matching the window frames. The louvre blades are in RAL 9007 Grey Aluminium. Both are manufactured from marine-grade aluminium and rated for coastal environments.

Outcome

Post-installation monitoring showed a maximum interior temperature of 26.2°C on the hottest recorded day of the following summer — within the TM59 comfort threshold. The client reported that the central living space, previously abandoned from noon to early evening during warm weather, was now in use throughout the day. The smart home automation means the screens deploy and retract without manual intervention.