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Greendale Cottage

Phil & Joy Newbold undertook a self-build detached 3-bed Dales cottage using Passivhaus principles, in Upper Weardale, County Durham an Area of Outstanding Natural Beauty (AONB). As Phil is an architectural technician & Certified Passivhaus Consultant he undertook the project and site management and designed the house using Passivhaus principles and with the aid of Passive House Planning Package software. 21°’s PERFORMANCE windows, MVHR systems and airtightness products were specified for the project.

Planning issues in AONB

The project has faced a number of challenges, not least the planning requirements for a Conservation Area and a designated Area of Outstanding Natural Beauty. The Newbolds’ desire for a certified Passivhaus was scuppered by the planning department’s insistence that they retained the L-shaped floor plan of the original planning consent as well as insisting upon the house meeting local vernacular aesthetic requirements including random stone walls, natural slate roof and sliding sash windows. Despite not achieving Passivhaus certification criteria, the resulting home still achieves an impressive thermal performance with building fabric U-values of approx 0.1, an airtightness result of 0.59 @ 50 Pa and a predicted space heating requirement of around 18 kWh/m2/K.

Airtightness & woodburning stove

An unusual aspect of the project has been the use of a 10Kw Woodfire F12 room-sealed woodburning boiler stove. This is the home’s sole heating source and has a back boiler that provides up to 8.5Kw of hot water in the winter and also heats towel rails in the bathrooms plus a heat-leak radiator in the linen cupboard. Integrating the stove and masonry chimney stack within the timber frame structure was a challenge in itself. Airtightness detailing around the stove was achieved through using grommets around pipes with taped Pro Clima Intello membrane around any breaks through the timber frame. So, unusually for a Passivhaus-inspired project, the cottage has two chimneys stacks – one a false one for the MVHR air inlet and one for the twinwall stainless steel stove flue

Mock sliding sash triple glazed timber windows

21° supplied its triple glazed PERFORMANCE mock sliding sash windows and external doors for the project at a whole window U value of 0.91 W/m2K. The planning department had to inspect a sample of the window before approval and they were satisfied that it was a good facsimile of a sliding sash window.

21°s PERFORMANCE mock sliding sash gave the best thermal performance sliding sash type window that we could find. It is a tilt and turn inward opening window that gives a convincing outward appearance of a sliding sash window. We were relieved that it met with the planning department’s approval. We have been more than happy with the windows – they do what they say on the tin!

Phil Newbold - Client

MVHR heat recovery ventilation

21° also designed, supplied and commissioned the PAUL Novus 300 MVHR system for the project. Phil installed the rigid steel ducting as well as the MVHR unit himself.

21°s MVHR department did a fantastic job. What was really useful was being able to transpose the MVHR design software into the timber frame software so that the timber frame company knew where to create pockets within the timber frame structure for the ducting pipes etc. I also liked the way the ducting plugged together. 21°s MVHR team were very patient with us and MVHR Technical Consultant, Andrew Farr, was like a dog with a bone, balancing the inlets and outlets, sorting any problems out and ‘interrogating’ the electronics. We have been very pleased with the quietness and efficiency of the MVHR system in general – you can only really hear it faintly when it is in boost mode after we’ve had a shower or been cooking – not like the noisy extractor fans in most homes.

Phil Newbold - Client

Airtightness measures

21° also supplied Pro Clima airtightness products such as Intello Plus membrane, cable and pipe grommets and Tescon tape.

Project details


The project won the the National Award for “Best New Home” at the 2014 LABC Building Excellence Awards.



Life changing homes