Re: Re: Energy Efficiency/New Building Regulations
what is your definition of air tightness? Building regs call up a minimum amount of trickle ventilation – otherwise we’d all suffocate. Has anyone actually recalculated the figures to check whether, under the new Part L requirements, the min trickle vent amounts are sufficient to sustain life??? I can tell you one thing – the air tightness requirements cause air pressure levels that result in the standard chain door closers being unable to close the inner doors in apartments – this is a small, minor issue of life and death, that directly contravenes part B.
air tightness as defined by Part L have nothing to do with passive ventilation, or anything at all to do with Part F ‘Ventilation’. Anyone who has done an air tightness test knows that all passive vents are sealed. The test is to calculate the air permeability of the construction method. In this calculation, the rate of ‘tightness’ and ‘permeability’ are essentially the same thing… the measurement is a rate, and therefore can be examined directly against ‘tightness’ or ‘permeability’. It is used simply as a factor in calculation the energy efficiency of buildings.
Permeability of a construction method does not allow us to breathe, as defined by the building regs. Engineered ventilation allows an adequate supply for fresh air to buildings in order to ventilate pollutants and exhausted gases and prevent excessive condensation.
munsterman, you are correct in that a building looses heat through both passive ventilation and building permeability. However, for the purposes of calculating energy efficiency of a building method, the passive ventilation factor is not included.