Sips - MVHR

[Taff]

We have decided on a sips installation, do we need MVHR, we are not passive, and will be using an ASHP with UFH. 

[ProDave]

You may not be passive, but I would expect it to be to a reasonable level of insulation.

 

If you put in the detail to make it reasonably air tight as well, then MVHR is the final bit of the jigsaw to get your heating bills down to the minimum.

[Taff]

If we chose not to have a MVHR would we have issues with moisture seems it will be a tight building 

[ProDave]

Why are you against MVHR?

 

A new build near my tried to get away with just trickle vents, but the air test result was too good and BC insisted he fit MVHR to the property.

[jfb]

Sips should be reasonably airtight as a build method without going the extra mile .  I would just plan for Mvhr from the outset and make sure it's as airtight as you can get.

[Roundtuit]

You need to be pretty airtight to make it worthwhile, but having lived with mvhr for 18 months, I think the 'heat recovery' part is possibly the lesser of the benefits. Having a controlled directional air flow through the house, constant fresh air into bedrooms and living rooms, and extract from kitchen/utility/bathrooms I think is just great. There's a gentle background noise to ours; just enough to tell when the the humidity sensor has detected our teenage daughters extended shower so I can shout up the stairs in a father-like manner.  Our sons bedroom no longer smells like he's keeping ferrets in there.  Stuff dries quickly; towels/tea towels, laundry dries over night in the utility room. If I had to live in a house without it now, I'd definitely miss it.

 

[Dreadnaught]

@Roundtuit, reduced amounts of dust inside?

[Taff]

Hmmmmm, sounds like I need to find a budget to invest. Would it be a massive issue if we were to fit this after the build as we haven’t allowed for this in our plans or budget!

[Mr Punter]

5 minutes ago, Taff said:

Hmmmmm, sounds like I need to find a budget to invest. Would it be a massive issue if we were to fit this after the build as we haven’t allowed for this in our plans or budget!

 

You would need to do all the ducting and room terminals plus electrics and condense drain but you could leave buying the unit until later.

[jfb]

As punter suggests - much much trickier to retrofit.

Edited February 24, 2020 by jfb

[Roundtuit]

14 hours ago, Dreadnaught said:

@Roundtuit, reduced amounts of dust inside?

 

Difficult to say.  Possibly, the filters certainly catch a lot, but I suspect that most household dust is created 'in house' so I couldn't vouch for that as a benefit.  Probably keeps some pollen out though.

[Roundtuit]

11 hours ago, Taff said:

Hmmmmm, sounds like I need to find a budget to invest. Would it be a massive issue if we were to fit this after the build as we haven’t allowed for this in our plans or budget!

No, but you need to give it some thought.  As above, you'd need to get the 'infrastructure' in during the build, but that's not a massive outlay if you install it yourself.  Air tightness is key to effective mvhr, so for me, the bigger consideration would be whether to spec your windows without trickle vents (and I would suggest that would be the preferable in the long term), and how you achieve adequate ventilation levels in the interim.

[Jeremy Harris]

We find that we don't get anywhere near as much dust in this house as we did in our last house.  I suspect that some of this is down to the filtered air coming in through the MVHR and some is down to the absence of any drafts from the good airtightness.  Having lived in a house with MVHR there's no way I could live in one without it now.  The biggest single thing we've noticed in the house has been the really good air quality.  If I had to list the benefits of MVHR then I think the 80% reduction in ventilation heat loss rate would be quite well down the list (even though that takes a massive chunk out of our heating bill).  Air quality has to be top of the list, along with the absence of condensation and the way there are never any lingering smells.  The way things like towels dry very quickly is another really noticeable advantage.  The airtightness also makes the house pretty quiet, almost spookily quiet at times, as with no open windows for ventilation outside noise is pretty much kept out.

[Taff]

On 24/02/2020 at 22:21, Roundtuit said:

No, but you need to give it some thought.  As above, you'd need to get the 'infrastructure' in during the build, but that's not a massive outlay if you install it yourself.  Air tightness is key to effective mvhr, so for me, the bigger consideration would be whether to spec your windows without trickle vents (and I would suggest that would be the preferable in the long term), and how you achieve adequate ventilation levels in the interim.

Yes we have opted for no trickle vents, aluminium with glass at uvalue of 1.1wkm, build is sips with 25 mm kingspan insulation to help reduce uvalue further.

[Taff]

On 24/02/2020 at 22:49, Jeremy Harris said:

We find that we don't get anywhere near as much dust in this house as we did in our last house.  I suspect that some of this is down to the filtered air coming in through the MVHR and some is down to the absence of any drafts from the good airtightness.  Having lived in a house with MVHR there's no way I could live in one without it now.  The biggest single thing we've noticed in the house has been the really good air quality.  If I had to list the benefits of MVHR then I think the 80% reduction in ventilation heat loss rate would be quite well down the list (even though that takes a massive chunk out of our heating bill).  Air quality has to be top of the list, along with the absence of condensation and the way there are never any lingering smells.  The way things like towels dry very quickly is another really noticeable advantage.  The airtightness also makes the house pretty quiet, almost spookily quiet at times, as with no open windows for ventilation outside noise is pretty much kept out.

Are you using a heat pump with this

[Jeremy Harris]

9 minutes ago, Taff said:

Are you using a heat pump with this

 

 

Yes, but it doesn't really need very much heating in winter at all.  Worst case we need about 1.6 kW of heating (so about 0.5 kW of electricity) to keep the house warm when it's -10°C outside.  We've never had temperatures that low, and on average the heating seems to come on for a few hours overnight once every day or two in winter.  It's not unusual to go for a couple of days without the heating coming on on milder days, like this past weekend.

[Taff]

Perfect, is it a ashp? Are you using UFH?

[Jeremy Harris]

4 minutes ago, Taff said:

Perfect, is it a ashp? Are you using UFH?

 

 

Yes, a small ASHP that runs UFH that's built-in to the insulated ground floor slab.  We have no heating upstairs, apart from towel rails in the bathrooms, and don't need any, as the bedrooms stay at a comfortable temperature.

[Taff]

Lovely, what type of installation did you use on the slab?

 

[Jeremy Harris]

26 minutes ago, Taff said:

Lovely, what type of installation did you use on the slab?

 

 

We just cable tied the pipes to the steel reinforcement mesh before the slab was poured.  There's some details in our blog, here: http://www.mayfly.eu/2013/10/part-sixteen-fun-and-games-in-the-mud/

[Roundtuit]

2 hours ago, Taff said:

Yes we have opted for no trickle vents, aluminium with glass at uvalue of 1.1wkm, build is sips with 25 mm kingspan insulation to help reduce uvalue further.

Good plan.   How were you planning to ventilate then?  I assume the 25mm is an additional (internal) layer?  What's insulation is in the SIP out of interest?

Edited February 26, 2020 by Roundtuit

[Taff]

14 minutes ago, Roundtuit said:

Good plan.   How were you planning to ventilate then?  I assume the 25mm is an additional (internal) layer?  What's insulation is in the SIP out of interest?

Open a window ? my architect hasn’t questioned any of it there’s extraction fans in kitchen/bathrooms etc. Each time I read something crops up so now guessing I best plan for this. Yes it’s additional and takes the uvalue down further

 

sip info 

Kingspan TEK™ utilises Kingspan’s high performance, fibre-free rigid thermoset Urethane Insulation for the core of the SIP panels, which is autohesively* bonded and sandwiched between two sheets of oriented strand board (OSB/3). 

[Taff]

1 hour ago, Jeremy Harris said:

 

We just cable tied the pipes to the steel reinforcement mesh before the slab was poured.  There's some details in our blog, here: http://www.mayfly.eu/2013/10/part-sixteen-fun-and-games-in-the-mud/

Loving the blog some interesting reading! Think that’s the plan they have in mind we’ll i hope it is 

[Roundtuit]

43 minutes ago, Taff said:

Open a window ? my architect hasn’t questioned any of it 

 

Yeah.. not sure that's going to do it!  If your architect is also doing Building Regs application for you, they'll  have something in mind I would think.  Probably worth having the chat about windows without trickle vents if you haven't already...

[Taff]

Yes I have a list of questions so that’ll be added, we have independent building inspection tho