Zero Carbon House, Hertfordshire
Architect's Team: Rebecca Birch, Luisa Sommerer, Yusra Osman, Sam Launders
Planning permission: Granted November 2021
Contractor: Harris Calnan
Structural Engineer: Term Engineering Studio
Area: 350 sq m
Completion: Due 2024
This is the home of a family of 4 on the site of a 1950’s bungalow originally constructed by the owners' grandparents. It is a long narrow suburban site in a neighbourhood comprising a mixture of single and two storey detached homes in a wide variety of sizes and styles. The house references the dominant chalet bungalow style while also taking its key materials of red brick and plain tiles as a memory of the bungalow previously on the site.
The house sits on the footprint of the bungalow and is necessarily compact in plan to avoid overshadowing and overwhelming its neighbours. The whole house revolves around a 3-storey top lit central atrium and stairwell which introduces daylight to the centre of the plan.
The garage is under the house in a basement accessed via a car lift. This avoids the deadening effect of garage doors on the front elevation and the typically suburban but unfortunate barrier of multiple cars parked in front of the house and creating a barrier between the home and the public realm of the street.
The design has been assessed through an embodied carbon calculator. It is designed to be whole life net zero carbon. The house has been designed to meet the RIBA 2030 Climate Challenge standards for operational energy use and embodied carbon. The standard includes a maximum annual energy consumption of 35 kWh/m2/yr. This is supplied by 7.2kWp output roof mounted photovoltaic cells and the house is heated via a ground source heat pump and passive solar gain collected in a South facing sunroom. There is a wood burning stove in the sitting room and the flue is routed through the centre of the house to ensure maximum heat is retained in the building.
Walls are thick and super insulated and floor construction is concrete giving a high thermal mass. Walls and roof have a U value of 0.1 W/m2K and windows are triple glazed. The flat roof of the sunroom has the additional protection of a sedum roof.
South facing glazing is protected from overheating by sliding shutters to the first floor bedrooms and a roof overhang with extendable awning to the ground floor sunroom glazing.
Air quality is maintained throughout the year by a whole house ventilation system with heat recovery which runs at a slow and constant rate.
Rainwater is collected in a large tank under the patio and used in toilets and appliances and to water the garden.
We endeavour to source 80% of building materials within 75 miles of the building site to reduce energy use in transportation.