Part l passive house heat requirements

liamdenn

Hi guys
I am confused about the above.
If we were to build a house to near passive standards with MHRV without much additional heat requirements does it comply with part l?
We were thinking of a stove with 2 kW to the room and 8kw to the water and then simple electric heaters for the relatively few nights when it is -6 or whatever as a back up. Seems a nice simple solution without the need for an expensive "central heating" setup.
Would love to hear from anyone who has experience of this problem.
Thanks
Liam

BryanF

Part l 2011 requires a renewables %

The ber will take the electric heating as priminary source

This will not meet building regs

Get your arch / ber assessor to advise

greenfit

Hi Liamdenn

BryanF is correct. Electric heating will be considered the primary fuel and you will never get compliance. But why not try it without electric heating altogether? It is true if your habitable rooms are without heat emitters the BER assessor assumes electric heating anyway. However, there is a way around this in a highly insulated dwelling like yours. See attached technical guidance. The important thing is that the design heat loss (DHL) is under 3kW. I know it says 'small' dwellings, but how is that defined? It would have to be determined by the calculation. If you are worried about a chill on cold nights, you could plumb in towel rails from your stove which wouldn't be a big job.

If you are unable to make sense of the attached, just put it to your BER assessor.

Calahonda52

A back boiler-ed stove is not that simple a solution, especially if you consider all the work involved with keeping a stove stoked for hot water: ashes, fuel storage, cleaning, as well as the need for a stove that will pass muster with MHRV, not to mind what happens when you can no longer bend down to stoke it!.

Don't work with deap or ber or Part L so what follows is just a question for tose who know:

what about inline elec or hot water coils in the MHRV...... the hot water coils could be driven from a reversible heat pump to provide chilling if required to deal with high levels of humidity in summer, which was an issue this year in parts of Ireland.

sydthebeat

liamdenn wrote: »

Hi guys
I am confused about the above.
If we were to build a house to near passive standards with MHRV without much additional heat requirements does it comply with part l?
We were thinking of a stove with 2 kW to the room and 8kw to the water and then simple electric heaters for the relatively few nights when it is -6 or whatever as a back up. Seems a nice simple solution without the need for an expensive "central heating" setup.
Would love to hear from anyone who has experience of this problem.
Thanks
Liam

this is the issue.....

how far can you stretch the elastic before "near passive" isnt accepted?

actually, whether or not a "totally passive certified" build is accepted as being building regulation compliant is down to the individual building control officer of the area. Its not a guarantee.

the ONLY way to be building regulation compliant in a prima facia manner is to have a preliminary assessment done before you start and then build totally to that specification. If you change the specification during the build, you need to get the changes assessed before incorporation to see their knock on effects.

simply saying we will have a low energy demand therefore we are regulation compliant doesnt wash with anyone. MHRV is pretty much standard now for regulation compliant post 2011 homes.

sydthebeat

Calahonda52 wrote: »

Don't work with deap or ber or Part L so what follows is just a question for tose who know:

what about inline elec or hot water coils in the MHRV...... the hot water coils could be driven from a reversible heat pump to provide chilling if required to deal with high levels of humidity in summer, which was an issue this year in parts of Ireland.

there was two houses constructed in carlow a few years ago which were passive certified houses but only reached a BER rating of B2 IIRC, so technically wouldnt have complied with b regs.

they were heated by an electric element in the MHRV system.
very economical, very cost effective, a great way to provide for the low level energy demand. The main space heating source was solar gains.

However in DEAP there is no way to include solar gains as your main space heating source, and using DEAPs conventions electricity had to be inputted as the main heating fuel... which destroys your rating due to its 2.8 conversion factor (at that time. its now down to about 2.25 i think)

gooner99

Was in a low energy near passive house. Heating was a stove with back boiler. Stove gravity fed to the hot tank. Solar panels also fed to the hot tank. There were towel radiators in the two bathrooms. Mvhr also installed. Solar gain to South. Seemed to be working fine. But as others have said tending a stove can be quite a bit of work. Having said that I'd say at least half of the houses built Today have a stove. I've also heard of another very similar stove only setup where the house owner placed an mvhr extract in the hotpress. Thought that a very smart idea. No solar panels installed, the guy figured hot water from the stove along with a timed immerion made more sense.