Zoo

@Nickfromwales and @SteamyTea this is all remarkably helpful. A lot of homework you've set me. thank you.

Should I consider a UVC then? As I say, we’re not terribly flush for plant space.

@PeterW Cheers for this information

ProDave you have made it look beautifully simple and if I do end up going this route, I will be coming to you for support! What system do you purchase from BPC and how many wetrooms and outlet rooms did you have to lay ducting to? My other concern is a poorly installled MVHR system not perform well.

My quote from BPC was £1200 for the unit (Vent Axia) and £1k for the ducting. I would also need to get it installed as sadly I don't have the skills. I've had quotes from the usual guys - CVC Airflow, Total home ranging from £3-5k which I was expecting. Then the DCV was brought up which I'm exploring on the basis of capital cost, running cost, maintenance, IAQ, control and commissioning as it seems to have something in it, but I don't yet have enough information to confirm any claims or merits.

It's also a slight issue for me that I've only found one company (possibly two) that supply DCV in the UK.

I do have a quote for the DCV. Design and supply only. To cover 4 wet rooms and 5 rooms with air inlets. Doesn't include ducting which is bog standard 204x60mm or 125Ømm ducting. The claim is that the installed cost of DCV is usually approx. 60% the installed cost of an MVHR system

My concern with DCV has always been thermal comfort. The answer I've received from that is the volume of air entering is quite low so the energy required to maintain the temperature isn't significant in a modern, well-constructed air tight building with very modest space heating demands.

The architect did say that! I should trust his judgement a little more

This forum made me aware of MBC and also Touchwood Homes then I met two other self builders independently of this forum who were very happy with choosing MBC. All ticks in the right box but not enough for the final sway. Sat down with the final three contending quotes, MBC, JML (SIPs) and Bentley (SIPs) all pretty much the same price. Came down to thinness of external walls (our plot is not that big) and craneage included in the price or not.

I have the utmost respect for both tried and tested and for forging a different route. There are merits and pitfalls to each. I am interested in something a little less explored in this particular instance because i like the idea of DCV and it warrants further exploration. It is not enough for me to go with what's tried and tested for its own sake if there is a possibility of something else out there that is equivalent or even superior when matched up. BTW I too considered the SIPS route very seriously, but decided in the end to go with none other than MBC!

We'll have mains gas which is relatively cheap hence why the architect wants to use it. Combi boiler though?

Right! I actually don't mind being a maverick, but i do want to be armed with as much information asIi can before taking a leap into the unknown! A building control engineer I know has confirmed that it does meet Part F ventilation and part L low energy of the English B Regs.

That's the point I'm trying to articulate to my architect. Thank you. I have just downloaded @JSHarris heat loss calculator and will plug in our values if this is a good starting point. But then what? Have not discounted PV, just thought they might be out of our league price-wise. The EPDM roof will have a 12 degree slope and fully waterproofed with drainpipes and guttering.

Afternoon all I'm a new member and I'm planning to build a timber frame home with a target fabric air tightness of 1 ACH and the u-values of the home will be 0.14 w/m2. On the good advice of others, I had only ever considered MVHR as an option for our ventilation solution. Though the cost makes me shudder a little. However, I recently spoke to a consultant who spoke about ventilation strategies and suggested many options I hadn't even heard of. Some not appropriate for my build e.g passive stack, but one that caught my attention - Demand Controlled Ventilation. . It's an occupancy and humidity controlled system that uses CO2 sensors and humidity sensitive extract grilles and air inlets that react to occupation in rooms whereas MVHR runs at the the same rate whether the house is occupied or empty. There were points that made it sound like a credible alternative to MVHR. However, it is not a heat recovery system and doesn't temper the air that goes back into the room. The eyebrow raiser for me is that I don't know of ANY private residential project in the UK that has heard of it let alone installed it! Commercial yes, student accommodation, apartments yes. Ireland and mainland Europe yes. I have scoured this site high and low and not a mention of DCV within the most clued-up, switched-on self build community. Anyone know anything about it - good, bad, ugly?