Heating, cooling and hot water for new 30 square meter space above garage

[JHH]

I should be very grateful for some advice, please. I am creating a small self-contained liveable space (about 30 m²) above my existing garage. There will be a small kitchen area, living area, bed and a separate small bathroom.   There will be an almost flat roof with opening roof lights with blinds but not sun protection glass - in total 7 m² .There will be no other windows and the ceiling height will be 2m. The new space will be well insulated and the space below will remain as a garage and a cool space. The new space could have a variety of uses, including a home office or guest accommodation and needs to have space heating, hot water and because of solar gain, some way to cool it when necessary There is no room for an external heat pump or photovoltaic panels.

 

I’m trying to find a solution that’s ecologically sound and reasonably economical to buy and run, and my research has thrown up the following, most of which appear to have a draw-back.

 

1 A wet system with radiators and electric boiler. (no cooling) 

2 Infra-red heaters . (no cooling or hot water)

3 All-electric radiators such as those supplied by Sunflow,Adax and Climastar (no cooling or hot water)

4 ”Air conditioning and heating unit such as Powrmatic Vision LTHW (fan coil model) Twin Duct PTAC Air Conditioner and Heat Pump - VIS-LTHW” (cooling but no hot water, noisy?)

5 An air to water heat pump such as Ecocentric or Groundsun200 which as I understand it will produce some cooling but probably not enough as the bathroom and kitchen may not be producing much warm air if the space is used as an office.

 

Please does anyone have any advice on the above or alternative solutions. It appears that most of the drawbacks can be mitigated by buying additional units, but I would prefer a simple integrated solution if possible.

[SteamyTea]

Probably need a lot more information for a definitive answer. Knowing the surface to volume ration helps, cooling is nearly all about volume.

PV on a roof will take out energy when it is sunny, reducing heat load. 

Also have a look at air to air heat pumps, they can heat and cool, and are very cheap.

How do you want to deal with domestic hot water, stored or instantaneous?

30 m² is 2/5 the size of my place, and I use night storage heaters and a 200lt hot water cylinder.

[joth]

Will the bathroom  have a shower or bath? This is the greatest impact on DHW design, everything else could be met with modest instantaneous direct electric heater. 

Aside from that, +1 to air to air heat pump (i.e. your option #4)

 

[JHH]

Thank you both for your replies.  Unfortunately we do not have space for a PV.

As a complete novice I am not sure how I calculate surface to volume ratio. The dimensions are height 2m, width 5m, depth 6m.

We would consider stored or instantaneous hot water.

The bathroom will have a shower only and the kitchen will be part of the living area with a small sink.

Do either of you have experience of air to air heat pumps? I have looked at the electriQ 10000 BTU wall mounted and others.  As it would be in the living/sleeping area I am concerned that they could be too noisy? Would you have all air to air or combine with simple electric heaters?

Do you have any views on infra-red heaters?

Since the area is so small, I wonder whether we should just go for an electric combi boiler which would solve my water and space heating and then buy a fan to at least get some air circulation when it is hot.

 

[TonyT]

What spare capacity does the house consumer unit have?

do you know the size of the cut out fuse?

helpful info for pointing the design one way or another?

[PeterW]

1 hour ago, JHH said:

Thank you both for your replies.  Unfortunately we do not have space for a PV.

As a complete novice I am not sure how I calculate surface to volume ratio. The dimensions are height 2m, width 5m, depth 6m.

We would consider stored or instantaneous hot water.

The bathroom will have a shower only and the kitchen will be part of the living area with a small sink.

Do either of you have experience of air to air heat pumps? I have looked at the electriQ 10000 BTU wall mounted and others.  As it would be in the living/sleeping area I am concerned that they could be too noisy? Would you have all air to air or combine with simple electric heaters?

Do you have any views on infra-red heaters?

Since the area is so small, I wonder whether we should just go for an electric combi boiler which would solve my water and space heating and then buy a fan to at least get some air circulation when it is hot.

 

Electric Combi is a complete no unless you have very deep pockets. It will chew electric like it is going out of fashion. 
 

2m height is very low - why the low ceiling ..?

 

And do you have BRegs/planning for any of this ..?

[Ferdinand]

I doubt whether a 2m ceiling will meet Building Regs. There is no formal limit afaik, but docs such as the London Space Standard suggest 2.2m.

 

I think you need more like 2.2m or 2.3m.

 

2.3m is really the minimum which is comfortable imo.

 

Phone your Buildings Regs debt to check.

For heating I would perhaps consider one of those single room reversible heat pumps you mention, and an in line Electric Heater for water - but for cost you will want short durations showers ? .

 

It's really all affected by the purpose  eg is it an annexe, or a posh spare bedroom, or with a separate entrance. Then you have things like eg Council Tax to think about.

 

There's a lot of stuff to go  into - I would start with talking it through with a professional, or the Council.

[ProDave]

3 minutes ago, Ferdinand said:

I doubt whether a 2m ceiling will meet Building Regs.

 

I think you need more like 2.2m or 2.3m.

 

2.3m is really the minimum which is comfortable.

 

Phone your Buildings Regs debt to check.

2M will.  I thought building regs demanded 2M over stairs and a landing without actually specifying a minimum anywhere else?

 

But stairs up from a garage, only roof windows in a 2M ceiling (too high for means of escape) are the starters for why this would not pass BR.

[JHH]

Thanks for your attention to this. We have consulted an electrician and unfortunately we need a new electricity supply. I should have said that we have full planning permission and building control.  The garage is listed and is in a conservation area, so the roof is as high as the planners would allow. The ceiling height is 2.3 m at one end and 1.95m at the other – not ideal but it was that or nothing. There’s a fire-proof staircase between the downstairs garage and the upper space We’re embarking on this project since the existing garage (with asbestos and leaking roof) needs total refurbishment so we thought we’d take the opportunity to create the extra space, with no single use currently in mind.

[TonyT]

Air to air for the heating and cooling with a cylinder for hot water with a 3kW immersion, would doubt that a new supply is required for that?

 

[JHH]

Thanks Tony.  You are right, but we plan to put an electric car charging points n the garage space which I understand takes quite a load.

Does anyone have experience of the air to air heater/coolers with the air inlet and outlet to an external wall? Or does anyone have experience of infra red heaters?

[SteamyTea]

3 minutes ago, JHH said:

Or does anyone have experience of infra red heaters

Forget about them, they are not for domestic settings.

[JHH]

Thanks - is there a particular reason?

[SteamyTea]

5 minutes ago, JHH said:

Thanks - is there a particular reason?

They are just electrical resistance heaters which don't heat the stuff you want warm.

They rely on public ignorance of science.

[JHH]

Thanks for your prompt response.  Do you have any experience of air to air units like the  ElectriQ 10000 BTU for heating and cooling?