UK manufactured products

WINDOWS

The quality of the windows are critical in not only hitting our aspirational space heating target of 30 kWh/m2/yr, but also from a thermal comfort perspective. There are a number of Passivhaus window manufactures in mainland Europe, but they all appear to only manufacture inward opening windows which are not suitable for the project house.

We contacted Munster Windows who have factories in Ireland (good from the Northern Ireland angle) and England. They are just bringing to market their outward opening 'PassiV' window and so we are in the process of obtaining the technical data required for input into PHPP. Its been a bit of a struggle as they are being asked for data which isnt normally printed in glossy brochures. But, we are getting there.......

The next question is the type of frame, PVC-U or timber? HA's favour low maintenance PVC-U. Window manufacturers wont commit to a performance guarantee on wood frames only commenting that they 'may last up to 20 years'. This means the possibility of 3 sets of windows between now and 2050, plus the associated stripping out and replacement of the internal insulation in the window reveals (how sustainable is this option?). Hence considering PVC-U with closed cell foam filled frames and quadruple glazing units to compensate for the higher U-value of the frame when compared to a thermally broken wood frame. Thermoplastics including PVC-U can be recycled up to around 10 times (according to the British Plastics Federation) but checking to see if the addition of a foam infill impacts on this.

Finding a closed cell foam to create a thermal break between the frame and the masonary proved time consuming. Eventually we came across Kewell Converters Ltd who produce a suitable foam in strip form.

BOILER

Due to the low space heat demand, we have tried to source a boiler of around 4kW to prevent boiler cycling. Although there are a couple of manufacturers of such a boiler in Germany, even though CE marked, apparently these do not have type approval for use in the UK.

Having attempted to convince a few manufacturers that there will be a demand for small boilers in the not too distant future, none would commit to the project and conjure up a small boiler. Choosing a boiler was also frustrated by manufacturers reluctance to provide technical information.

A Worcester Bosch 12kW systems boiler has been chosen not only as it appears to be the smallest genuinely UK manufactured unit available, but also the company provided all the technical information requested.

MVHR

A comment on the feed back from the TSB judges was that we should endeavor to use a locally made MVHR. We have been scouring the UK for a suitable unit, however, although often promoted as a UK product, it appears that many of the parts are made in distant countries such as China with the unit assembled in mainland Europe. These MVHR's therefore have no distinct advantage over the preferred choice of a Paul MVHR from Germany which has Passivhaus approval. Also, the specific fan power used by many other MVHR's is appreciably higher (+30%) and the heat recovery less efficient than the Paul. Worcester Bosch (our choice for the boiler) have an MVHR being lunched in the UK this summer, however, this is manufactured in Germany and doesnt have the same efficiency as the Paul.

An additional requirement is that as the project house is a mile form the Belfast Lough, the MVHR heat exchanger needs to be made of plastic (as in a Paul unit) so it doesnt suffer corrosion from the salt laden air. The vast majority of heat exchangers in MVHRs appear to be alumiminum which renders them unsuitable.

Currently, although enquiries are continually being made with 'UK manufactures' of MVHR's, a Paul unit is the front runner.Retrofit measures In order to establish the appropriate retrofit technologies, a sensitivity analysis using PHPP (Passivhaus Planning Package) was carried out. The metrics for each selected technology were entered into PHPP individually and their affect on the dwellings overall energy balance analysed using the PHPP model of the existing house as the base line.