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A_L last won the day on October 12

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  1. You have moisture condensing on the joists and insulation? The question has to be, where is it coming from? There are two possible answers 1) the warm room above, or 2) from the cellar below, either through external air entering through air-bricks or because the cellar is inherently damp. If case 1) then a vapour control layer (VCL) is required to prevent water vapour reaching and condensing on the cold joists. This could be foil faced and taped Celotex. You can then insulate between joists as normal. If case 2) then insulation below the floor joist is required to keep them warm and prevent condensation and an air barrier, to prevent bulk movement of air to the joists would be useful. This is a very complex area. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14655&page=1 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14655&page=1
  2. For the same thickness of material 0.05 is twice as insulating as 0.1. as pdf27 says for UFH you do not want the floorcovering to be too insulating because you have to have the floor at a higher temperature to achieve the same output. On the TOG scale your 5.5mm Fibreboard is TOG = 1.1, so is slightly more insulating than the others. However the effect appears to be quite small, see page 11 here - http://www.johnguest.com/wp-content/uploads/2014/07/UFH-Tech-Doc-Z2105-387-0914WEB.pdf
  3. @Ian The inserts can been seen on page 24 here - http://www.nudura.com/docs/default-source/brochures/nudura-product-guide.pdf?sfvrsn=4 They seem to go inside the form and do not increase its width. @LadyBuilder 55mm of K5 has the same insulating effect as 100mm of the polystyrene they use
  4. - The previous hot water, 5019kWh is unusually high, what happened to reduce it so dramatically? - In case you missed it I made some comments on floor insulation savings on page 1.
  5. Temperature Constant

    @Barney12- Do you have any thoughts on the outgoing dT of 7°C with an incoming dT of 13°C? Airflows not yet balanced? Lots of condensate? Incoming reduced to protect heat exchanger?
  6. - here are several possible options foamglas - https://uk.foamglas.com/en-gb/applications/foamglas-perinsul marmox thermoblock - http://www.marmox.co.uk/products/thermoblock purenit - http://en.puren.com/fileadmin/user_upload/products/industrie/purenit/en/Purenit_ENGLISCH_2016_SCREEN.pdf compacfoam - http://www.compacfoam.com/26-compressive-strength.html - none are exactly cheap though.
  7. - if this means, as it suggests, that you have moved from an off-peak tariff to a daytime tariff it will be seriously deleterious to your EPC Band. Probably a two band reduction (or more). Particularly since the DHW heating is now also likely to be daytime. - If someone with storage rads and an off-pk tariff has a single immersion 110litre DHW cylinder one of the most effective steps is to install a 210litre twin immersion cylinder
  8. - a reduction of floor U-value from 0.23 to 0.18 will save about 4kWh/yr/m2 , a reduction to 0.1 will save about 9kWh/yr/m2 (Full SAP model) - I know from the winter of 2010 I could heat my house, on a continuous basis, with 6kW heat input. - A quick estimate using your existing U-values suggests a 7KW boiler size (including hot water), so I think a 10kW ASHP with appropriate heat emitters would do already.
  9. a - I currently live in a 68m2 version, admittedly with a 20m2 extension, so I hope I can say I have some experience. c - with your existing floor insulation nothing additional here would be economic f - If that is 10000kWh/yr for space heating and DHW then £500 energy costs implies around 5p/kWh for energy. I think given current off-peak and daytime electricity rates only an ASHP running at a COP of 3.5 or better could achieve this, with spare P.V. heating DHW to relieve the ASHP of the high temp/low COP end of the DHW.
  10. Celotex Thermal Performance

    Something else is the reduction in R value as the temperature drops with falling exterior temps. This is American so have to divide by about 5.7 to get S.I. R values https://buildingscience.com/documents/information-sheets/info-502-temperature-dependent-r-value The R values of fibrous insulation tend to increase with falling temps.
  11. Additional insulation?

    @ProDave , in theory yes but in practice it is possibly more complicated. Your current garage wall has a thermal resistance of about 4.5K.m2/W (15mmOSB 190mm Frametherm/timber), the unventilated service void only contributes 0.18K.m2/W, or about 4%. 82mm of Frametherm 35 has the same thermal resistance as 100mm of Pavatex, so 100mm in practice. Putting this on the outside will 1) lose floor area in garage and 2) require larger timbers to attach plasterboard? If the service void is 47/50mm I would put 50mm Frametherm here and 50mm on the outside, adding 2.68K.m2/W (2.86-0.18) to the thermal resistance where Pavatex would have added 2.33. If the service void is only 25mm I would put 25mm of PIR/PUR/Phenolic in there with 50mm Frametherm on the outside, adding about 2.25K.m2/W (1.0+1.43-0.18)
  12. Additional insulation?

    You will benefit from the extra thermal resistance of the mineral wool but will lose the thermal resistance of the unventilated cavity (service zone). This will reduce the added thermal resistance by about 13%. Assuming a lambda of 0.036 for the mineral wool the U=0.15 will fall to about 0.13, saving around 1 to 2kWh/m2 /yr (Full SAP model)
  13. You need to get an On Construction Domestic Energy Assessor (OCDEA) to generate an 'as built' SAP score from which he will create the first EPC. This cannot be done by an 'ordinary' SAP/EPC Assessor as they can only use RdSAP on existing buildings. You need and air tightness test result for the 'as built' SAP score, there is a default option but it is probably to high for you to pass if the house is built to the minimum required to pass building regs.
  14. @johny_99 - to get condensing you only need to keep the return (to boiler) below 56/57°C, the flow can be higher. Any reasonable amount of condensing will get 10-15% more heat from the same amount of gas. Depending on the design of the system you could get a flow temp of 65°C and still be deeply condensing. I would aim for a return around 50°C. A conventional radiator at 60°C will give out about 40% more heat than at 50°C.
  15. - Improving a U = 0.1 construction with 50mm of PIR will save between 1 and 2 kWh per annum per m2 in a U.K. climate