More this month on the topic that is going to occupy the industry a lot over the next few months – the revision to the Building Regulations and, in particular, Part L – conservation of heat and power. I included some information in previous articles. (You can read old articles on www.pauljervis.net). In fact, this column seems to be evolving into an Building Regulation monthly update. I promise to try and include other topics in future but it’s difficult when this is the most important thing coming our way. It is the main element of the Government’s desire to have all new homes zero carbon by 2016 and non-dwellings by 2019 (probably). This latter date has yet to be confirmed as there are major obstacles with the differences in the uses of non-domestic buildings. A warehouse will have a completely different energy usage pattern than a computer facility running large numbers of energy consuming, heat generating servers, for instance.

The process of revising Part L has begun. The timescale is incredibly tight. The intention is for the revisions to take effect in 2010 (with subsequent amendments taking effect in 2013 and 2016). For this to happen, the new Approved Documents will need to be completed in draft form by the end of this year for formal consultation to take place in early 2009. Further revisions would then be made after examination of the comments received during the consultation phase and the documents then approved in October 2009. There would then be a 6 month run in period before the provisions become mandatory in April 2010.

The work involved in developing proposals has been broken up into bite sized chunks with glazing being one of the sub-working groups that has been named the Fenestration Industry Thermal Performance  Working Group (FITPWG). I have written previously about the high level focus on U values rather than the overall energy performance of a window and much effort is being made to educate non-window specialists that solar gain is important. It is a source of free energy that cannot be ignored.

As an industry, we have been asked to provide technical specifications and costs for windows with various U values down to 0.7. This does not mean that such low U values will necessarily be required. It is just to find out what the costs will be. What was decided at a recent FITPWG meeting was to try and provide data at increments of 0.1 U value to see where the tipping point is, i.e., where the cost increases dramatically for little gain in U value. At the same time, the figures produced will be used in the Standard Assessment Procedure (SAP) calculations used for determining the carbon emissions of new houses. It is anticipated that the energy savings gained by lowering U values will be largely offset by lowering the solar gains. It is anticipated that we can determine what the most effective point is for windows to contribute to the energy performance of the houses without entailing either technologies that are not available in sufficient quantities or excessive costs. New technologies could include vacuum sealed units. These are available in, I think, Japan, and provide thermal performance equivalent to double glazing at a thickness not much more than single glazing. They can also be incorporated into a sealed unit with another pane of glass with a low e coating and gas filled. But the supply to switch over to these kind of units is not available here and costs are unknown. Then there is the framing material. Timber and PVC-U can be thermally improved sufficiently to achieve very low U values but at a cost. I’ve provided examples previously of PassivHaus windows with timber frames incorporating a thermal break and PVC-U frames with foam filled external chambers. All well and good for demonstration projects but to switch over production of all windows to this type? Somehow I don’t think the figures will stack up. Re-tooling the PVC-U extrusion industry would run into billions and would take years and years.  For metal windows, improving the frames to such an extent would not even be possible and I’m sure that there is no intention to do away with aluminium and steel.

As an industry, we have to come up with persuasive figures to show what we can reasonably do for each of the step changes up to 2016. We are being pushed to make big improvements. In new build we should be able to show that very low U values are ineffective, cost too much and would need a supply of specialist glazing products which are not available in commercial quantities. If we can end up with sensible provisions in new build based on the overall energy performance of the window we could then expect that windows of similar performance levels for replacements would be specified. Currently, we have Window Energy Ratings included in the Approved Document for existing domestic dwellings with Band E required for replacement windows and Band D for extensions. Limiting U values are also included. One suggestion has been to propose that a WER Band C be required for replacement windows in 2010 which can be readily achieved with current technology without excessive costs rising to Band B in 2013 and Band A in 2016. These seem like logical steps and will therefore be rejected (that’s my cynical side showing).

Working out what the extra costs would be is also a problem due to commercial confidentiality and competition law. The glass industry knows to its cost what breaching competition law can mean! We have proposed therefore that those companies willing to carry out the calculations use a standard 2006 compliant window in accordance with BS 7412, BS 644, BS 6510 and BS 4873 as a cost base index level of 100 and to the produce index levels for each step down in U values. These figures will then be sent to a neutral party (me for PVC-U) and then averaged to show the percentage on costs will be. Hopefully this will identify the tipping mentioned previously.

And then we have conservatories. There was a major push some years ago to bring all but the smallest conservatories under full Building Regulation control which we managed to get stopped due the immensely high additional costs involved (estimates ranged from £400 million to over £800 million). However, it is claimed that we are now using conservatories more as a room all year round and that we heat them to a comfortable temperature thus increasing CO2 emissions dramatically. We may need to agree on a compromise where we accept that conservatory window, door and roof elements meet the same WER criteria as replacement windows. This should not be too burdensome as most companies will use their standard windows as the walls of their conservatories. What we must avoid is the application of all the other parts of the Building Regulations with the resultant additional costs that that would entail.

Hope this hasn’t bored you too much, but it really does matter.

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