MEV or DCV?

jasgrif11

I recently had a heat loss survey carried out in my house and the results were 3.05 m3/hr/m2 @50 Pascals pressure differential or 2.75 ACH.

My house is a 2008 build (2 story block construction, 150/100/150, UFH) with a vaulted hall and attic space to the left and right (2 separate attics).
The survey recommended increased ventilation and listed Mechanical Extract Ventilation (MEV) or Demand Controlled Ventilation(DCV) as possible solutions. I have researched both but I'm unsure which to go for and would like some advice.

I have existing wall vents, which are mechanically controlled (basically they are a 150mm hole and the vent will open/close depending on the outside temp.). Can I use these with DCV instead or having to change them all for humidity controlled vents (therefore lowering the expense).

As far as the controlled unit (which will be housed in the attic), I need two of these as I have two separate attics. I was planning to have these fed from the vent in a bathroom.

I know we can't recommend companies, but I also haven't found many and would like A PM if you have a recommendation.

Thanks
J

Calahonda52

1: what you mean by ...as possible solutions?

Solutions to what?

2: so the existing has no permanent ventilation, which means it both non-compliant with building regs and a possible death trap

3: Without addressing the ACH you run the risk of even greater heat loss

hatchman

A possible death trap ? Why ?

jasgrif11

While the house performed well during the air tightness test, there were some weaknesses uncovered, which are cumulative in nature resulting in discomfort during windy weather. Insulation levels are adequate but needs attention in areas where is has been disturbed / compressed / missing. This has since been addressed.
There are signs, in areas of thermal bridging, that the ventilation system/strategy (ventilation is by way of intermittent mechanical extractor in the kitchen and bathrooms with adjustable hole in wall vents in every room) is barely adequate and will need to be addressed (upgraded) to maintain a dry and healthy internal living environment.

I have managed to address some of the easier air leakage issues (however the house was never constructed with air tightness in mind and I fully understand that).
Next I would like to upgrade my ventilation in order to maintain a healthy environment. So back to my original question, is there anyone in a similar situation and have they installed an MEV or DCV? How airtight does a house need to be in order to go with a DCV? Based on my results would you recommend one or the other?

Calahonda52

hatchman wrote: »

A possible death trap ? Why ?

He says all the vents are temp controlled so at certain times all the vents are shut:
he may have some fossil fuelled appliance in the house which generates CO if not properly set up....

jasgrif11

nope just UFH, as stated in my original post