Energy Efficient Home
When Colin Usher and his family wanted to build an affordable, energy efficient home, they didn’t have to look far for a designer. Mr Usher is a director and one of the founders of John McCall Architects, a firm with a proven track record on sustainable building design. Mr Usher and the architects were able to design a two story, four bedroom home in West Kirby, England for a price of £240,000 ($340,000US). According to the architects, the price is on par with other houses with similar size and amenities.
Since the house was built two years ago, the Usher family’s total energy bill - heating, cooling, and electricity - has been £15 ($21US) per year. A similar house designed to meet normal building regulations would use £2500 ($3550US) worth of energy each year. Besides saving money on energy bills, the family sleeps well at night, knowing that their home’s annual carbon footprint is a paltry 11 kg of CO2.
The house’s shell consists of 150mm (6”) concrete blocks, giving a maintenance-free exterior and a significant thermal mass. Interior walls made of 100mm (4”) concrete coupled with 200mm concrete floors add to the thermal mass, which helps retain heat in the winter and curtail solar warming in the summer. Windows and doors made of triple-glazed glass help to minimize heat loss. Turning off the heat in the winter results in an indoor temperature drop of only one degree Celsius per day.
The building is so air-tight that fans are needed to bring in fresh air. The mechanical ventilation system includes a heat exchanger to extract heat from the exiting air and transfer it to the incoming air.
An air-to-water air source heat pump (ASHP) delivers both space heating and hot water. The heat pump draws heat from the outdoors, brings it inside, and heats water in the underfloor pipes. The ASHP also heats water in a storage tank, serving all the hot water needs of the household.
In the summer, the ASHP can work in reverse, transferring indoor heat to the outside - a system better known as central air conditioning. However, this is rarely needed, because the house was designed to facilitate cooling by natural convection. The lower story ceilings are 3 meters (10’) high, allowing heat to rise and be absorbed by the concrete floor above. The staircase provides a chimney effect, pulling hot air directly upstairs, where it can be vented outside through a pair of roof windows. In the summer of 2014, with no air conditioning used, the indoor temperature never rose above 22C (72F) downstairs and 24C (75F) upstairs.
Designed using Passivhaus concepts, the Usher house actually exceeds Passivhaus performance standards by a factor of four.
Solar Power and Electrical Efficiency
All of the energy used by the house comes from electricity, so it seems natural to generate as much as possible on-site. A grid-tied solar array consisting of eighteen photovoltaic panels is integrated into the south-facing roof, delivering more than 3300 kWh of electricity every year. The integrated roof panels were chosen for ease of maintenance as well as aesthetics.
All appliances meet the highest standards for energy efficiency. Daylighting provides enough natural illumination that nobody needs to flip a light switch until nightfall; of course, the electric bulbs are energy efficient LEDs.
Designed with BIM
Building Information Modeling (BIM) was used throughout the design process. In addition to being a 3D architectural CAD tool, BIM allows architects to model and simulate all aspects of the building’s performance. Using these models, designers can choose materials and systems that optimize energy use. Here are some of the factors that Mr Usher took into account when designing this house:
The Award Winning Usher House
The Usher House recently won the Domestic New Build category of the Buildings and Energy Efficiency Awards. Upon receiving the award, homeowner Colin Usher said, “We are delighted to have won this award because it proves eco homes don’t have to be over expensive or need to be conspicuously unconventional in appearance.”
Speaking of unconventional, gothic fiction author Edgar Allen Poe’s catalog includes a horror story called “The Fall of the House of Usher.” While Poe’s spooky tale gave chills to his readers, England’s award winning, energy efficient “house of Usher” won’t frighten anyone … except maybe the power company.
Here’s a short BBC News story on the Usher home:
Video credit: BBC
Images courtesy of John McCall Architects