Friday, 3 June 2011

sustainable housing update courtesy of NHBC conference

1. The coaltion want to reduce regulations but some anxieties/upcoming activities from CLG included:
  • CLG (Building Regs) Minister Andrew Stunnell very exercised by compliance failure 
  • Zero Carbon now means CSH 5 but 'Code 6 is not dead' 
  • security 
  • rainwater-harvesting 
  • ecology 
  • embodied carbon 
  • ventilation and over-heating 
  • health and lifetime homes 

Watch for the release of the National Planning Policy Framework proposals, soon

2. Some news form the Zero Carbon Hub included:
  • Carbon compliance is a minimum standard of fabric and technologies but this is now based on emissions/m2 rather than percentage improvements - much better! But the variation in UK weather is a huge problem; SAP assumes we all live in Nottingham 
  • Cyril Sweett have reported that the extra over cost of a Code 5 (ie new ZC) home will have come down to £10k by 2016.

3. BRE have studied Greenwatt Way in Slough and concluded, among other things, that MVHR can be problematic:
  • the need for a better research into how MVHR works (or doesnt)
  • need to insulate MVHR ductwork in cold roofs 
  • watch out for noise from fans 
  • it can cost £20 to change the filters 
  • better not to put the MVHR in the attic for ease of maintenance access - think about putting it in a cupboard, although this can conflict with need for storage space; dont forget the condensate pipe
  • try to minimise the duct runs and ensure the flexible ducting isnt kinked etc

4. Lessons from Joseph Rowntree Floundation's Elm Tree Mews in York included:
  • Airtighness target was 3m3/m2 but it measured bewteen 6 and 9m3; luckily the ventilation had been designed thinking the target was 10! 
  • Co-heating tests showed up massive fabric failure in part due to construction of presinsulated timber cassettes in a wet summer; wet warmcell insulation had to be replaced and there was much more timber in the cassettes than anticipated leading to U-value deteriorating from 0.18 to 0.3 
  • locally sourced windows claimed a u-value of 1.5 but that was mid-point not overall as specified, so rated 2.0 overall 
  • complex shapes and contextual arts and crafts detailing led to extensive cold bridging 
  • solar thermal only worked in one home - problems included a nail through a pipe, kinked pipework and one with the flow and return fitted the wrong way round 
  • tenants didn know how to use the winter gardens and used them for storage 
  • each dwelling had 4 controllers - heat pump, space heaing, solar hot water and immersion heater! 
Let me know if you want to see the powerpoints.

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