An innovative sustainable home the Backgammon project is a 330-sqm new build house in the Buckinghamshire countryside created by Dr Kerry Mashford and Dr Frank Ainscow with architect Jason King of BE Consultants.  The clients have extensive experience in the field of sustainable design having constructed their previous family home as part of the Future World project in Milton Keynes.  Kerry is also Lead Technologist on the Low Impact Building Strategy Board and has previously collaborated with VELFAC on commercial projects in her position as Head of Sustainable Manufacturing & Construction at Ove Arup & Partners Ltd.  The aspiration behind this project was to combine contemporary, practical design with sustainable materials and methods and intelligent building controls to significantly reduce energy usage.  VELFAC glazing played a key role in achieving these aims.

VELFAC windows provide free energy

The Design - the house has been designed to optimise solar heat gain and daylight levels, therefore reducing the energy demands and operational costs of the completed building.  The southern elevation has 65 sqm of triple-glazed, argon-filled VELFAC 200 series windows, shaded from the midday summer sun by a first floor balcony, while the remaining facades have smaller glazed areas.  Slim frames and mullions allow for a greater percentage of glass resulting in a high Ff value and therefore superior daylight levels.

While the balcony prevents overheating in the summer months, the high thermal performance of these windows allows for generous glazed areas without compromising on heat loss.  The glazing provides 92 kWh of solar gain per day in September, 57 kWh per day in October and 60 kWh per day in May.  When combined with heat created by occupant activity and appliances this solar gain means the house only requires supplementary heating from November to April.

Winter garden - A double-storey winter garden comprising double-glazed, argon filled VELFAC units has been attached to the west elevation.  This structure effectively acts as an additional heat reserve in the winter and a cooling device in the summer as a second inner screen of glazing divides the winter garden from the house interior and is equipped with automated vents that allow air to either enter or escape the main living space.

In the winter months the glass structure helps to cool the house by drawing warm air from the house into the winter garden, while trickly vents and open windows on the northern facade create a cool air flow through the building.  On sunny days in the colder months, the winter garden fills with heated air and a destratifyer pumps this warm air from the top of the winter garden to the bottom allowing it to then enter the house.

The entire process is automated as opening vents within the winter garden facade employ actuators concealed within the VELFAC windows.  An integrated WindowMaster control system operates this ventilation system, opening and closing windows in response to temperature senors within the building.

Working with VELFAC from start to finish

The consultation process - vital to the success of the project was the collaboration between the client and VELFAC from the very early design stage.  This process is to be encouraged with all projects, both residential and commercial, as it can lead to significant time and cost savings as well as the specification of the correct VELFAC products to ensure optimum performance and energy savings.

Kerry and Frank initially approached VELFAC with feasibility drawings and sketches.  The technical team was then able to discuss the exact design and strategy behind the project before suggesting specific products once variables such as the weight, size and range of glass had been considered.  At this stage the VELFAC technical team can provide real time data, including the U-values, Light Transmission levels and solar shading coefficient for each of the individual glazing units and run a range of scenarios through the VELFAC costing programme to test the viability of the design.

The information enables the service engineer to accurately predict how the building will perform, ideally at the feasibility modal stage.  As every VELFAC glazing unitl is bespoke and made to order the client and VELFAC can then work together to tweak the design and ensure the best possible outcome before the design is finalised.

Full design package - in order to achieve the air permeability target for the Backgammon project of 3m3/m2/hr at 50 pa, VELFAC was instrumental in the installation process, designing the interface between the window and structure for each individual unit.

Customer support - the relationship between client and VELFAC continues right the way through the construction process and beyond.  As with every VELFAC client, Kerry and Frank continue to have access to the customer service team who can deal with any future challenges such as a broken pane of glass.