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A_L last won the day on October 12 2017

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  1. @Dreadnaught & @HerbJ Yes it should also prevent loss of heat exchange efficiency when temperature falls below zero in winter, down to -6°C according to Paul. I am sure at one point Paul claimed down to -20°C. Repeating the links I gave in an earlier post on this thread. Theory here:- https://www.paulheatrecovery.co.uk/components/moisture-heat-exchanger/ Edit: no longer seems to work http://waermetauscher.paul-lueftung.de/en/product-information/enthalpy-exchangers-erv.html 2nd Edit: @Dreadnaught managed to get a copy and saved as PDF PaulenthalpypageasPDF.pdf
  2. A_L

    Retrofit Party Wall Insulation

    Would sealing the top and bottom of the cavity not be sufficient? Assumes sides are already sealed by CWI?
  3. Which MVHR do you have? At least some can be optionally fitted with an enthalpy (or latent heat) heat exchanger. This allows water vapour in the exiting air to transfer to the incoming air, humidifying it. Particularly useful in cold conditions where the incoming air has little water vapour but should also help in summer. Theory here:- https://www.paulheatrecovery.co.uk/components/moisture-heat-exchanger/ http://waermetauscher.paul-lueftung.de/en/product-information/enthalpy-exchangers-erv.html It should also prevent loss of heat exchange efficiency when temperature falls below zero in winter, down to -6°C according to Paul.
  4. A_L

    Airtightness and Vapour Control:

    Is it to naive to ask........... - Consider two means of transport of water molecules, 1) Bulk air movement 2)Vapour diffusion. These have to be handled differently. Bulk air movement caused by say a convection current from a radiator or by an air pressure differential, carries water molecules along. Vapour diffusion occurs when there is a concentration gradient of water molecules, in this case the molecules in the more concentrated areas move to the less concentrated areas in an effort to maximise their path lengths before another collision with another water molecule. An air tightness layer therefore may or may not control both mechanisms. If it does not provide resistance to water vapour diffusion and it is inappropriately sited then interstitial condensation may occur in appropriate circumstances. Vapour Control ..... So you need roofing felt (vapour control) allowing the vapour to exit, but not return. - Not quite, you need to allow water vapour to exit but prevent the return of liquid water needs BOTH a VCL and an air-tightness layer prevent vapour leaving the house by using the air-tightness layer as a VCL?.............potentially, but this will towards the inside of the structure and you will probably need something, i.e. more membrane, to protect the external sheathing for example. prevent ingress of vapour in the same way?........vapour ingress in our climate is not normally a problem as it is usually warmer inside than out and the incoming water molecules will not condense as the Rh falls as they move inwards. And put the air-tightness layer where there are least penetrations? ..... preferable but case dependent, on the outside it must not be water vapour resistant or interstitial condensation may occur unless another VCL present on the warm side or preferably use a breathing construction which is not subject to interstitial condensation
  5. All your windows "pass" on U-values. IIRC WER band "C" or Uw<=1.6W/m2.°C to pass. Windows are the very last place to look for "easy" SAP points, the difference between your worst and best will be marginal.
  6. I think males of all bees are stingless, certainly hive and bumblebees are. No room for stings and reproductive organs in the abdomen. You are unlikely to encounter many though, mating requires fatal disruption of abdomen. They lay a few eggs in tube like structures and seal them over and then start on a new tube, usually immediately close by. Yes they do like hot dry conditions.
  7. A_L

    Self Build Timberframe in Nottinghamshire

    TER is 'Target Emmission Rate', the amount of carbon produced in heating a house with the same footprint as yours and with levels of insulation, infiltration and heating system as specified in the building regs. Your house DER, 'Dwelling emission rate' must be less than the TER. You specify an air change per hour rate (ACH). For passivhous it is 0.6ACH@50Pa. I suggest you aim at 1-3ACH@50Pa to make effective use of an MVHR. This is a leakage rate at an elevated pressure, the actual unpressurised uncontrolled (infiltration) rate will be considerably lower, about 1/20th if IIRC. If designed in from the start Passivhous need only be 0% to 20% more expensive.
  8. The floor perimeter must also be measured on the inner face of the external walls (heat loss walls only).
  9. A_L

    25mm EPS vs PIR

    One way to look at is to say 38mm of EPS has the same insulating effect as 23mm of PIR, so not quite twice as good. The proportions hold for other thicknesses
  10. The link does appear to make an allowance for the efficiency of converting input fuel to output heat but I am sure that the RHI payment is only based on the energy provided by e.g. the ASHP to heat the house i.e. the previous system is disregarded. It may be that a coal house, with a chimney, is draughtier and thus is assessed as taking more to energy to heat. Because you have a cavity wall the EPC will not have a EWI recommendation. Even if you had a solid wall and it recommended EWI this recommendation is disregarded for RHI purposes
  11. Since it is an existing house I think an assessment could be done on the basis of electric instantaneous heating. However the heating system does not affect the total heat demand, which is dependent on the heat losses. IIRC if the EPC has recommendations the heat demand figure for the RHI payment will be based on the heat demand with the recommendations implemented. If you have <= 150mm loft insulation then 270mm will be recommended and if no CWI this will be recommended, if <80mm jacket on DHW cylinder then improvement also recommended. There may be other relevant recommendations.
  12. The phase change will occur at a temperature lower than the fridge uses so will not store/release energy.
  13. I have astigmatism and I am significantly short sighted. I have been told that I am not suitable for varifocals/bifocals. I have a pair of glasses where one lens (the right) is for reading and the other for long distance. Seems to work O.K. for me.
  14. If you mean "attract" a swarm, swarms have scout bees which search for a suitable location, typically a dark void of a couple of cubic feet. It helps to put honeycomb which has previously been used to raise bees in the "bait" hive as it gives off an odour which the bees like. If a swarm is hanging from somewhere it can gently be dislodged into a box and the mass of bees moved later and tipped out in front of a hive when they will run into the hive. The trick is to get the queen in there as the bees follow her odour.