Heat recovery system Vs Trickle vents

ecaf

We are starting a new build and we are getting conflicting advise regarding the different systems available to us.
I'm trying to research as much as I can to try and make the decision. Basically I thought we'd be going with the heat recovery system, but the architect and builder are both against them. And have offered a solution of "trickle vents" in the windows as our ventilation, with additional extractor fans in bathrooms and kitchens.
The builder is so down on the HRV that I'm having problems talking the OH around. He reckons heat recovery are not much good except in bungalows maybe, and they are a waste in two storey houses, especially having to drill through all the joists, etc. (I would have thought the installation company did this anyway, so it shouldn't be his concern) Anyway apparently they are a complete waste of money!!!
Any help, tips, experience much appreciated please?

sydthebeat

First question, have you had your provisional BER assessment done to see what you need to do to comply with Building regulations? if so did the assessor give you a break down on the "with HRV" specification versus the "without HRV" specification.??

HRV actually suits two storey dwelling much better than single storey as less pipe runs mean more efficiencies and less costs.

You wouldnt drill through all the joists, you would suspend the lower ceiling.


You can have a look here for starters and see what others think of their systems.

some points i would say:
1. if your builder is so against the system i certainly wouldnt trust him / her to either know, or pay attention to, the specific workmanship details that are required for a successful system. Personally i wouldn't install a HRV system into a build that didnt achieve at least a result of 3.0 in a blower door test.

2. convince your OH from a fuel saving point of view. use this analogy:
The trickle vents in the windows will change all the air in a room 4 times in every hour. That means that radiator has to heat the room 4 times every hour. A HRV system running at 75% efficiency will instead only need to heat the whole room once every four hours as it retains 75% of the heat on every air change. That means in effect that the trickle vent system uses 16 times the amount of fuel as a HRV system.
Put on top of that that the HRV is a more balanced, draught free system.

They do not come without maintenance, so dont expect it to be a "plug in and forget about" system as they need filters changed etc.

If its any solace, the vast majority of houses built under the new 2011 regulations will require HRV systems to comply with minimum regulations, so you could be seeing to 'future proof' your build.

ecaf

Thanks for your reply sydthebeat. I didn't know about the suspended ceiling or that it was even an option. I'm trying my best to get my head around all this terminology, from Solar / HRV / Windows / Stoves & heating radiators or not... etc.
There was mention about the provisional BER assessment, I'll have to follow him up with a phone call and get more details. We are in a badly built cold house with drafts coming in from everywhere. I just keep getting told that it will be a million times better than this and it will be done "properly". I'll take a look at the other thread you linked to.

Someone else mentioned to me at the weekend about getting HRV and an intello membrane. I know someone with a timberframe and this membrane, but because we were going with blocks I didn't realise it was something that could be done with blocks too. Will this be something the BER assessor will tell me about?

sydthebeat

you need to start with a provisional assessment straight away.

If the assessor is good and capable, it will open your eyes to the level of detail thats needed to, at a minimum, comply with building regulations.

Tapes and membranes are a lot more applicable to timber frame houses than masonry, but there are some situations in which they should be used in masonry houses. It depends on the design, features and level of air tightness required.

All these details need to be look at holistically as a "whole view" rather than a piece by piece elemental view.

To be honest it doesnt sound like your architect has been very helpful with your questions, i wonder how much technical knowledge they have???

ecaf

Thanks I'll get onto the BER guy, I heard a B1 provisional rating being mentioned, but I don't know where that came out of and I was trying to find out so much about the other systems that I never thought of ringing him to find out more.

sydthebeat wrote: »

To be honest it doesnt sound like your architect has been very helpful with your questions, i wonder how much technical knowledge they have???

Yeah I'm wondering that too, between him and the builder they are stuck in the old days of building. Don't think they like being told about the new / alternative methods, maybe they think I'm trying to make them look bad, but all I want is not to waste money and to have a decent house by the end of it.

homewardbound11

Hi.
You seem to be at the stage where we were 3 years ago. I would make one suggestion and that would be to get as much education now and not to fall into any disbeliefs from trades or others. You must have an air tight house for hrv to work. So this is a cost you need to account for on top of the hrv. A blower test should reveal an air tight house a 3 should be easily made. With any detail a 1-2 should be normal. I am not sure of the 2011 regulations. But the difference in an a1/a2 rated house to what you are living in is no comparison. Our 2900 sq ft house heats for 1/2 the cost of our old 1000sq ft semi detached. That is down to air tightness and recovery and of course insulation
I do think you need to aproach a good ber agent as your architect is not helping. I had a similar experience. Hopefully the her agent can put you in contact with a company that will do both the hrv and airtightness and test afterwards
Having said all that. I still think the 5200,we spent on the hrv was too expensive even at 1/2 that cost.
Would I change away from the air tightness and insulation u values at passive levels. Never.

As syd said you are more than likely required to have it to comply with 2011 regulations. Expect quite a few changes to your
Plans after your preliminary bet. Especially in relation to heating systems and levels of insulation.
Ps . Tell your builder has he heard of web joists.they can accommodate the hrv ducting if he is worried.

MicktheMan

To the OP; the following is what I did today and most days are no different.

The client was a homeowner who built their house 2 years ago and were told it would have a "B1" energy rating. They called me because they were cold in the house and it wasn't from lack of burning oil. I surveyed the house and yes the insulation was there but no measures were taken wrt airtightness. When they saw and felt the volome of air leakage in the house and I explained what was happening / how it should have been done when building, they said "Why didn't we talk to you before we built". This is not the first time I've been asked this question.
So...
my advice is to listen to what others have said above and take action. It is next nigh to impossible to recify airtightness after the fact. If you think your architect and/or builder are not up to the job then find someone who is now. Also spend the few quid on a good ber assessor or energy consultant, it won't be a waste.