Concrete crafts an energy-efficient home

A concrete house has won the 2014 UK Greenbuild Awards Domestic Newbuild category, which honors the country’s best sustainable products and projects in the building industry. The award recognises the building’s energy consumption performance, falling far below the norm and exceeding Passive House criteria for energy conservation.


Rural Sussex in the south of England harbors the sunniest of the climates in the British Isles, and the location is also assaulted by the cool crosswinds and biting winter conditions of the English Channel. This coastal environment was damaging an aging, energy-consuming farmhouse that prompted the owners to brief Ecotecture architects to design a contemporary, energy-efficient home to replace the existing structure.


The dynamic house design is an eye-catching, award winning 410m² home nearly five times the size of average British new builds, yet far more energy efficient. That efficiency is built upon landscape features and Passive House design techniques that incorporate Insulating Concrete Forms (ICFs), a system known for significantly reducing energy usage. 

Named the “Curly House” for its unique curved shape that cuts into a hillside, grass roofs cool the building’s lower levels, which are set down into the rolling natural landscape. The building’s green architecture design helps distribute heat throughout using a natural ventilation strategy in conjunction with a mechanical ventilation heat recovery system. The crescent shaped structure of the Curly House capitalises on summertime and wintertime sun taking full advantage of its seasonal orientation for providing low energy consumption, following Passive House principles.


“The Curly House is an exceptional example of how low energy architecture does not necessarily equate to design limitations or inside of the box thinking” Jake White, Designer of Ecotecture 


The Curly House design emerged from combining three key design principles: its crescent form on plan, its stepped arrangement on the site and a curved sunshade structure to prevent the windows from over-heating. After considering numerous sustainable construction options, the builder recommended ICFs for the walls and an insulating concrete system for the floors and roof. These methods contributed thermal mass advantages that balance the heat gains and losses from the large areas of glazing.  

No timber was used in the construction of the building envelope. The semi-subterranean nature of the design meant that materials susceptible to damp could not be considered. The insulating element of the ICF system, along with the roof and floor system, acts as a buffer, allowing the slow release of heat into the building to ensure a constant internal temperature throughout the year. Once the ICF wall blocks and floor panels were positioned, a sustainable concrete mix was poured into the formwork, completing the floor and walls as a continuous element.

Energy Efficient and Durable

Thermal bridging was reduced greatly. Air tests show the house achieves a remarkably low 0.2 air changes per hour (ACH) by using ICFs and concrete, surpassing the air tightness standard required for Passive House compliance of 0.6 ACH. The Curly House will last a century, not decades like conventionally built houses, and will be passed from generation to generation.


Building with ICF's

Insulating Concrete Forms (ICFs) consist of fire-retardant polystyrene foam blocks or wall panels that are stacked, steel reinforced and filled with concrete, which completes wall construction in one easy step. During the last three decades, tens of thousands of ICF homes have been built in Europe and North America, testament to the high performance walls with substantial thermal mass and structural support.

Research shows that houses built with ICF exterior walls typically require 44% less energy to heat and 32% less energy to cool than comparable timber frame houses¹. The materials that make up ICF construction will normally suffer little or no degradation over the life of a building and ICF’s estimated durability is excellent. 

For more information on ICFs – click here.

¹ PCA RP119 VanderWerf, Energy Comparisons of Concrete Homes vs Wood Frame Homes

Project: The Curly House                                    

Location: Sussex, UK                                                

Photography: Jake White

Architect: Ecotecture Ltd, West Sussex, UK      

Builder: Kithurst Builders, Ltd, West Sussex, UK       

Engineer: BLB Chartered Engineers, UK

Concrete Systems: Walls - Insulated Concrete Formwork (ICF) by Nudura, floors and roof – Insulated Concrete by Op-Deck

Ref: Sharon Harper. Crafting the Curly House, Concrete Homes, September 2014