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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorzak99
    • CommentTimeApr 14th 2021
     
    Hi All,
    We live in a late 70's small detached 2/3 bed bungalow in a rural village with no gas, so run an old Oil boiler, still going strong but old `and noisy so its turned off at night. We are near the coast of a large estuary and next to a field so exposed to wind. The place is really cold in the morning and takes hours of the boiler flat out to get warm. The floor is a concrete slab, with the pipes to old but solid radiators in a screed about 50mm thick and the walls brick and block with rockwool insulated cavity. Theres 200mm in the loft floor and double glazed all round but its ancient, cold to touch the aluminium frame and draughty and on the list to do. It's just me and the wife. We also run an old wood burner with a mix of wood, briquettes or eco logs and heavily depend on that in winter. This is of course an increasing concern regarding environment, climate etc and also health of internal air.
    My thoughts have turned to the possibility of AS/GSHP because of climate concerns, and especially because of awareness that the RHI ends next year. And perhaps upgrading the Wood burner itself along with more careful thought of what we burn. We have long considered a major refit including a well insulated loft conversion and external cladding but this has been on hold due to long family health issues and bereavement but also long frustrations with finding the right architect and plan. We may get back to that when things settle down.
    I'm aware insulation is THE most important thing we can do, but the external cladding and windows are perhaps waiting on our decision on progressing the bigger plan or not. In the mean time I wondered can I progress with the heating, I appreciate this is probably the wrong way round.

    Despite the cost of boreholes I feel inclined towards GSHP, for a few reasons, one being the existing boiler location is by the middle a long narrow alleyway leaving limited space for an external unit. External cladding/insulation will also be a challenge there in the narrow alleyway, but perhaps there will be higher spec and thinner insulation I could use on that part when I get to it.

    I did have a quote from Kensa for GSHP based on 'as we are' and that that would probably cover us in a future scenario with extra loft rooms but much improved insulation all round. I know its incredibly vague but what are your initial thoughts please? I believe I need to get an EPC to establish scale of RHI, the cost is quite a shock but doable and easier over the 7 years assuming a decent RHI. Regardless the cost benefit analysis probably doesn't add up unless I factor in the greater good as its the right thing for emissions (assuming that stacks up). I haven't had a quote for boreholes yet but am guessing around £10k.

    I guess some would say just insulate and replace the oil boiler. I'm not averse to that once I could feel its a sound long term move ethically with regards to climate etc. Thats important to me.

    My wife's wise main concern is - will we be warm?, she feels the cold. I appreciate with HP the water will flow in the rads at a lower temp but could be on longer, perhaps if quieter left on a low level over night hopefully easing that cold spell in the mornings. Lower temp rads replacements perhaps a requirement.

    Any advise at this early stage welcome please
    •  
      CommentAuthordjh
    • CommentTimeApr 14th 2021
     
    As well as insulation, it is well worth thinking about airtightness especially if you are exposed to wind. You should also think about ventilation as well (ideally MVHR).

    You should start by estimating numbers for floor and wall areas and for heating energy consumed. A floor plan would be useful. I didn't understand what you meant by

    "the existing boiler location is by the middle a long narrow alleyway leaving limited space for an external unit. External cladding/insulation will also be a challenge there in the narrow alleyway"
    • CommentAuthorRobL
    • CommentTimeApr 14th 2021
     
    How much oil do you burn per year? And wood, if it's significant. That will estimate the present heatloss.

    You are right that insulation long term is the best investment - it doesn't need fixing like boilers and heatpumps. I'm suprised that you need an architect - is there a reason?
    When you can cope with the upheaval, a window and EWI retrofit sounds perfect. Thermally unbroken aluminium frame windows would always be a weakness, so should be replaced prior to EWI as it is more difficult to replace them afterwards.

    Of course you can do the ASHP/GSHP first - but ignoring the RHI bung they probably cost the same to run as an oil boiler - and then would be un-necessarily big when the insulation is there. I think oversized heatpumps are ok if they are inverter ones, ASHP(A2W) usually are now, as are air conditioners (A2A), but not so great when they are clunk-clunk on/off ones.

    For a quick single room fix for next winter, you could get an air conditioner - it would heat a single room, like a woodstove. Cost around £1k fitted, uses electricity, probably similar cost as oil to run but better environmentally and wouldn't be oversized after insulation. The A2A unit would give you maybe 3kWh of heat for every kWh costing 17p, while the oil boiler would give maybe 9kWh of heat for a litre of oil costing 40p - actually very similar. Oil prices must go up though, if we are ever to wean ourselves off the stuff.
    • CommentAuthorzak99
    • CommentTimeApr 14th 2021 edited
     
    Posted By: djhAs well as insulation, it is well worth thinking about airtightness especially if you are exposed to wind. You should also think about ventilation as well (ideally MVHR).

    You should start by estimating numbers for floor and wall areas and for heating energy consumed. A floor plan would be useful. I didn't understand what you meant by

    "the existing boiler location is by the middle a long narrow alleyway leaving limited space for an external unit. External cladding/insulation will also be a challenge there in the narrow alleyway"


    Thank you. re the last paragraph here, I meant there would be limited space in the alleyway for an ASHP outside unit. Also that as its a narrow alleyway I wouldn't want to put say 75 or 100 mm insulation on the long wall in that alleyway, hopefully something much thinner with good insulation values is available for that space.
    • CommentAuthorzak99
    • CommentTimeApr 14th 2021 edited
     
    Posted By: RobLHow much oil do you burn per year? And wood, if it's significant. That will estimate the present heatloss.

    You are right that insulation long term is the best investment - it doesn't need fixing like boilers and heatpumps. I'm suprised that you need an architect - is there a reason?
    When you can cope with the upheaval, a window and EWI retrofit sounds perfect. Thermally unbroken aluminium frame windows would always be a weakness, so should be replaced prior to EWI as it is more difficult to replace them afterwards.

    Of course you can do the ASHP/GSHP first - but ignoring the RHI bung they probably cost the same to run as an oil boiler - and then would be un-necessarily big when the insulation is there. I think oversized heatpumps are ok if they are inverter ones, ASHP(A2W) usually are now, as are air conditioners (A2A), but not so great when they are clunk-clunk on/off ones.

    For a quick single room fix for next winter, you could get an air conditioner - it would heat a single room, like a woodstove. Cost around £1k fitted, uses electricity, probably similar cost as oil to run but better environmentally and wouldn't be oversized after insulation. The A2A unit would give you maybe 3kWh of heat for every kWh costing 17p, while the oil boiler would give maybe 9kWh of heat for a litre of oil costing 40p - actually very similar. Oil prices must go up though, if we are ever to wean ourselves off the stuff.


    Thank you, very rough estimate of current useage between 1000 and 1400 litres of oil, say 16 x 25kg bags briquettes, 20 bags or more of wood.

    Architect is if we get the loft conversion or small extension done (its not very straight forward - being a fink truss roof and a less than ideal internal layout). But would also need planning for external cladding and possibly for windows I think ? Yes I'd like to get the windows done asap but is partly dependent on possible internal remodel due to stairs etc. We'd like something along the lines of Velfac type thing, which will I imagine be much deeper than window units we have so doing EWI soon after will hopefully allow a decent sill inside still and a reveal around window outside.
    • CommentAuthorowlman
    • CommentTimeApr 14th 2021 edited
     
    Posted By: zak99

    Thank you. re the last paragraph here, I meant there would be limited space in the alleyway for an ASHP outside unit. Also that as its a narrow alleyway I wouldn't want to put say 75 or 100 mm insulation on the long wall in that alleyway, hopefully something much thinner with good insulation values is available for that space.



    ASHPs can be remoted for quite a distance, if you're worried about connecting to existing indoor pipework.
    • CommentAuthorzak99
    • CommentTimeApr 14th 2021
     
    Posted By: owlman
    Posted By: zak99

    Thank you. re the last paragraph here, I meant there would be limited space in the alleyway for an ASHP outside unit. Also that as its a narrow alleyway I wouldn't want to put say 75 or 100 mm insulation on the long wall in that alleyway, hopefully something much thinner with good insulation values is available for that space.



    ASHPs can be remoted for quite a distance, if you're worried about connecting to existing indoor pipework.


    Ah thanks. in that case it would need to be about 8 metres minimum from existing boiler location, I'd imagine theres a fair loss in efficiency involved in that ? That said boreholes would be much further away with GSHP. I need to do more reading to understand !!!
    • CommentAuthorowlman
    • CommentTimeApr 14th 2021 edited
     
    Depending on manufacturer and model You can remote up to 30 metres + on A2A. I'm not sure about A2W, which is, I guess what you're mainly looking at given your GSHP query. I guess the remoting distance is dependant on type.

    With A2W you'll first have decide if you go for monobloc type where the outside/inside connecting pipework is water flow and return.
    Alternatively you could look at a split system, where the interconnecting pipework is refrigerant with a heat exchanger most likely located inside. The latter will need an "F" gas fitter to install, the former because of its construction can be fitted by heating engineers.
    I prefer the split systems when I last looked, although they are not the flavour of the moment, but that's just personal. When remoting they have their downside IMO.
    • CommentAuthorRobL
    • CommentTimeApr 14th 2021
     
    I think a lot of people intend to get GSHP, then change their mind after a quote or two then fit an A2W ASHP.

    From the oil and wood amounts, it seems as if around 15MWh of heat per year is provided at the moment. I would expect that to be 4 - 10MWh of heat / year after new windows and EWI are done, depending on airtightness and EWI thickness, attention to thermal bridge details, how much the internal temperature creeps up!

    The "sensible" approach is insulate first then fit the heatpump - this may be skewed due to RHI money, and also if there's house remodeling planned.

    You don't normally need planning permission to change windows. We had to get cut-down PP for EWI - in our area (Cambridge) the requirements are lower for it than general PP I think. They actually state that you don't generally need PP for EWI, unless it will look different. Which it almost always will!
  1.  
    Mostly it's been said, but in environmental terms a heatpump is so dramatically better than an oil boiler that it's best going straight for that and sorting the insulation or windows out later.

    Replacement oil boilers are apparently to be banned in England from 2030 so after that it may become more difficult to find service/repair companies.

    Have you thought about how to do hot tap water? Might need to add a cylinder if you don't already have one.
    •  
      CommentAuthordjh
    • CommentTimeApr 14th 2021
     
    Posted By: RobLshould be replaced prior to EWI as it is more difficult to replace them afterwards

    Or during the project.

    Posted By: zak99the alleyway

    Sorry, what alleyway? What does it look like, how are things arranged? I said a plan would help :bigsmile:

    hopefully something much thinner with good insulation values is available for that space

    Aerogel or VIP are the options, both very expensive.
    • CommentAuthorrevor
    • CommentTimeApr 18th 2021
     
    When we remodelled / improved our 1750's farmhouse we had a similar dilemma. We had been aware of HP for over 40 years as my FIL worked for an engineering company that was working on the development of HP. Having the space for GSHP, that was our 1st thought however the cost was quite phenomenal and we thought we would insulate insulate insulate and go for a lower tech option. Along with attention to detail around avoiding cold bridging, airtightness, capitalising on solar gain and using the thermal mass of the stone walls and solar thermal we ended up, having discounted pellet boiler (due to reported issues around reliability) with a not so friendly LPG boiler and bottle gas but this winter have only spent £300 on LPG. So I would go for the fabric first approach do as much as you can practically do on that front, as that will be an investment to lower bills in the future regardless of the fuel you choose. With electricity costs, according to the climate change committee rising until 2030, I would not like to be faced with the bills then as my tariff went up by 10% last year and will go up another 10% this May.
    •  
      CommentAuthorfostertom
    • CommentTimeApr 18th 2021 edited
     
    Posted By: revorelectricity costs, according to the climate change committee rising until 2030
    Thanks to govt saddling us with guaranteed purchase of nuclear electricity at absurd rate for decades, has to be covered in everyone's electric bill even as renewables costs plunge and plunge.
    • CommentAuthordereke
    • CommentTimeApr 19th 2021
     
    If you find a way to get an ASHP installed then you will have £10-12k left over to upgrade your insulation and windows!

    I wouldn't worry about GSHP being "better" than an ASHP. If it is sized and installed correctly both will provide you with the heat you need.
    • CommentAuthorphiledge
    • CommentTimeApr 19th 2021
     
    Posted By: zak99
    The place is really cold in the morning and takes hours of the boiler flat out to get warm.


    That doesnt sound right for a house with an insulated cavity and a fair bit of loft insulation. If your boiler is working and delivering hot water, Id be sorting out where the heat is going before updating the heating system. Whilst a HP may appear to be a green thing to do, youll be no better off comfortwise with all the heat leaking out of the house. Get the draughty windows sorted and maybe hire/buy a thermal imaging camera to track down the heat loss
    • CommentAuthorselly
    • CommentTimeApr 20th 2021
     
    I know a bloke who is a plumber who is ripping out his GSHP and putting a gas boiler back.

    Too pricey on electricity
    •  
      CommentAuthorfostertom
    • CommentTimeApr 21st 2021
     
    Careful about giving air to such sound-bite anecdotes, when it must actually be a story about incompetent spec/installation of the GSHP, expecting it to supply hi-temp rads or something. Wd be interesting to question 'the bloke' a bit.
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