Slim Frames help Rationel windows achieve Passivhaus Standard at a lower cost

WARM – Passivhaus energy consultants confirm energy efficiency in Rationel’s slim framed Danish timber window products. And comment that these windows can achieve Passivhaus Standards with slimmer frames, without thermal insulation in the frames, and at a lower cost.

Sally Godber, director says:

“We have found the air-tightness from a Rationel timber window product is very reliable, an essential marker for Passivhaus Standard. And where care has been taken in the window installation, the energy efficiency of the Rationel window can be better than more expensive products with thermal insulation in the frames and much thicker frames.“

Because of their elegant slim profiles, Rationel windows have more glass and less frame than many of their competitors, giving greater solar gains, and daylight for the same size windows.

Sally’s energy consultancy firm WARM advises clients on how to achieve the most energy efficient buildings in the UK today. And she regularly practices what she preaches, with a new office and a new four-bedroomed home in a Conservation Area in Plymouth. Sally says of her own new home,

“All the hard work and attention to energy efficiency went in to the design of the building fabric itself. The choice of Rationel’s windows was crucial to us achieving our energy efficiency goals.”

She continues,

“The house is a really simple and robust design using methods which are known to work. And so my home looks more like a traditional house – it doesn’t have a heat source pump or large expanses of glass. We focussed on making it very simple to build.”

“It’s a timber frame structure, with an insulated slab for the floor. We’ve used boarding on the inside and outside, created a void which was stuffed with insulation, rendered the outside walls, and with weather protection in the slate cladding the upper storey we followed the local vernacular building style.”

“We used predominantly Rationel top hung windows to give the opening sizes we needed in a single pane. Because we haven’t got lots of mullions it means again we have less frame and more glass (so more light and solar gains). This also has the advantage that with the restrictor on it still gives a significant opening in comparison to tilting windows.”

Sally used Rationel Aura timber windows with triple glazing, top guided, side-guided and entrance doors also from Rationel.

Good solid quality workmanship has characterised Rationel’s windows and doors since the first products were shipped in 1954. Rationel was founded in Denmark and has sales offices in the UK and Ireland. The firm manufactures energy saving timber and alu clad timber windows and composite doors. Rationel is part of the Dovista Group, which consists of ten leading door and window companies in Europe. Dovista AS is owned by VKR Holding and employs 13,500 people in more than 40 countries.