Ok don’t shoot me (heat pumps/ventilation)

[Nic]

Ok 

I know a bit but not a lot… so say I build an ICF small house say 150m2 get it air tight and as passiv as possible without a passiv certificate etc. I have installed a system like the total home environment system ( saw it at a show ) Now has anyone done this ( or a similar system) and not installed underfloor heating or any other heating in the house. Obviously the salesman said you wouldn’t need anything else it the house was up to passive ( or near) I think there also heated the hot water. I kinda know it’s a bit of a difficult ( or stupid ) question I also know if later you wanted to add retrofit is more expensive and a pain etc but I am curious if anyone here has done this and the pros an cons …. I hope you don’t mind the question 

[ProDave]

Do you have a link to the system you are thinking of?  It sounds like some form of combined mvhr / warm air heating system?

[JohnMo]

Passivhaus heating requirements are based around a ventilation system doing 0.3ACH and the amount of heat that air flow can delivery. That being 10W/m2 max, any more the dust in the air starts to smell burnt. 

 

You really need to do a whole house heat loss calc, to see where you are heating wise.  You could always back fill any heating short fall with electric panel heaters, for a couple of days a year.

 

You are bit vague on what your system is but is it a ventilation heat pump type of thing?

[Nic]

Sorry I think it was this or a bigger version of it . 
https://www.totalhome.co.uk/ventilation/?pid=594

 

early stages of my fact finding and drawing just being sorted .

the whole house heating calculatio, is that easy to do? 

[ProDave]

So it's a variation on an exhaust air heat pump?

 

I would avoid personally, because I don't like an "all eggs in one basket" solution.  If it breaks down, you have to fix it or replace the lot.  What guarantees of future serviceability are there?  I have heard storied on EAHP's not being repairable.

 

With a separate ASHP, hot water cylinder, UFH and MVHR there is less to replace if one major part fails and cannot be repaired.

[Nic]

Ok I guess I understand that principle 

thanks. 

[Conor]

If you hit the passive house specs and actually achieve the required performance, you need little or no additional heating input. That however is based on a load of assumptions and conditions around occupancy, habits and environment. Away on hols for a week in the winter? Your house will be freezing when you get back. Seldom used North facing box bedroom? It'll be chilly most of the winter.

 

Our architect specialises in passive house designs and told us he'd never spec a house without some sort of supplementary heating.  In reality, a couple towel rads and a storage heater or two will be all you need.

 

We're almost passive house standard (meet all the U value requirements, MVHR is certified but we're short on air tightness) and there no way we'd be without our underfloor heating. During the cold snap last Dec, it was on almost constantly.

[Gone West]

13 hours ago, Nic said:

I kinda know it’s a bit of a difficult ( or stupid ) question I also know if later you wanted to add retrofit is more expensive and a pain etc but I am curious if anyone here has done this and the pros an cons …. I hope you don’t mind the question 

Yes, we did it. We built a small, 130m2, to much better than minimum PH standards, house. We heated the whole house to 23C using three electric towel rails, one in each of the bathrooms and 250W electric UFH in the kitchen. We fitted the UFH because there was nowhere to fit a heated towel rail in the kitchen. We installed a Genvex Combi 185LS which provided MVHR, DHW and warm air heating through the MVHR ducting. The warm air heating only came on in the coldest periods. The Genvex unit had a 685W EASHP which heated the integral 185 litre DHW tank to 45C and warmed the air. It worked well but only because the house design was modelled very carefully using the PHPP. Energy usage was very low.

[Susie]

We are in a similar position also ICF hopefully very good airtight, (no foundations yet) we are doing a lot our selves so plan to lay UFH pipes and see how warm it feels, then decide on installing the manifold. We will probably be a few years until finished so have plenty time to make changes if necessary.

Have you heard of a Willis heater it’s a bit like the internal element of a hot water cylinder plumbed into the UFH system.  It could do a whole house or a few rooms. Zoneing or not zoneing the UFH is a decision to read up about.

Any solar and batteries being considered? Even in winter we get some sun and together with off peak charging taking the chill of the floor may be all you need to ‘feel’ warm. 
Any other heating e.g. wood burner, stove.

 

[LSB]

We saw a system at a show called Unico which 'does it all', this is a hot air system, HID loved it and wanted to install.

We rejected because I'm very sensitive to air flow and couldn't face the thought of it coming in the room.

But, it did look quite good.

This was at the Swindon House Building show.

 

[Dreadnaught]

On 02/10/2023 at 20:40, Conor said:

Our architect specialises in passive house designs and told us he'd never spec a house without some sort of supplementary heating.

 

… and cooling. Often summer cooling is a greater challenge for a passive house than winter heating.

[Ferdinand]

On 02/10/2023 at 19:38, Nic said:

early stages of my fact finding and drawing just being sorted .

the whole house heating calculatio, is that easy to do? 

 

PHPP has been mentioned.

Also, one of our members created a spreadsheet which many have found useful. You may find this useful as a starting point. Here's the thread.

 

 

[Tim731]

You could get its big brother :

 

https://www.pichlerluft.at/pkom4-system-solution.html 

 

The PKOM 4 does have twin coils