trickle vents

I think the MVHR argument isn't so much about money/payback period or even heating bill savings; it's more to do with controlled ventilation being a positive to a healthier and better smelling home, with the heat recovery aspect playing second fiddle. Uncontrolled ventilation can't really compete other than on price, and the downsides that become apparent in subsequent years are difficult to quantify. Paying a few £K for no more farty bedrooms/mouldy bathrooms seemed like a ridiculous sum when I was laying it out (what? 2 ****ing fans in a box costs more than my car?) but I couldn't now do without it - it's worth that much in terms of earache reduction. One would imagine that the cost will reduce as uptake rises and true, it's not universally applicable or sensible but if the uk regs weren't so carp in terms of ventilation/draftproofing it'd make a huge amount of sense for new build..

Gary, you can always move into the extension and demo/rebuild the rest of the house?

Haha,u could lay off the curry instead
Agreed though, actually it's the heat exchanger that adds a lot of the cost, and the duct work. I managed to get a budget unit but still br compliant, I think max 260m3/h for only 150 on eBay, wouldn't have bother otherwise. But the duct was more cost in the end!