we are also building houses using cavity walls and are all in accordance with current regs and achieving B2 energy rating. I would love to hear anyones IINDEPENDENT) views on trying to find the balance between too air tight and too draughty.
it is going to be difficult from now on as we head towards even tough part L regulations. I'm an arch tech and certified passive house designer so I have my preferences but I'm certainly 'INDEPENDENT'
the current regs are finally addressing air-tightness, some would say our Regs are not going far enough, considering how far we've come with insulation.. I've just had a read of the new US codes (following a read of the greenbuilding advisor article) and they seem to be a small bit ahead of us in Ireland. But it's becoming clear that with increased air-tightness there are questions and decisions to be made regarding how we supply adequate fresh air to our new and retro-fitted homes.
So here's the thing, the PHPP insists on MVHR, and I for one do see the merit in its use. But then there's occupant behaviour, maintenance, initial product cost and electrical running costs to consider. There are also the irrational fears associated with units not working and the odd horror story that's pre-empted new codes of practice and safety features - But such fears can be applied to anything new, just like electricity less than 50 years ago. Now that's all mentioned, is there any alternative?
Is Demand controlled Mechanical ventilation an alternative to MVHR, when the overall running costs + initial set-up costs are considered? With DCMV's reduced electrical and primary energy consumption, is there some merit to this? It also has the bonus of having some of its kit already familiar to users as its includes direct extract fans at the usual kitchen & wc locations.
Irish Building regs & DEAP are crap and do not consider heat gains as being a major factor. they do not require a low enough air-tightness factor either.I do worry that some are calling this a natural or passive alternative to MVHR systems which they are not. although.. there are some completely passive system on the market but all have there issues, one is a window vent system that is of the market at the moment.. you may like to check-out the BedZed project its ventilation solution..