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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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  1.  
    At the moment totally renewable energy for heating and hot water using biomass but as I get older now looking at alternative technology and have seen the dramatic improvement in PVT and Heat Pump systems in particular what is being offered by Dutch company Agiba 2 power. Anyone with experience of such systems as they seem to have quite a few sites up and running in some quite harsh locations.
    •  
      CommentAuthorfostertom
    • CommentTime5 days ago
     
    What's PVT, and I can't find any 'Agiba 2 power' result that looks relevant?
  2.  
    PVT is a PV panel and thermal panel combined. They produce more electric than a PV panel in the summer as they keep the PV cooler whilst also producing hot water.

    link below

    https://agibaheating.com/2power-system/
  3.  
    This explains it a bit better

    https://triplesolar.eu/en/introduction/
    •  
      CommentAuthorfostertom
    • CommentTime5 days ago edited
     
    Thanks - I'd not heard it called PVT before, shd have guessed (or looked it up!).

    The Agiba site is hard to see that it's anything special. But looks like you're following developments and can interpret - so wd you like to outline how you'd see it configured as (part of?) a system and what kind of performance you'd hope for?

    As it stands, I'm advising clients that heat pumps aren't actually a substitute for a boiler unless the heat emitters can work at tepid temperature, which usually means a pretty well insulated house so heat demand is low relative to emitter surface area; then either UFH or the existing rads which after house insulation are well 'oversized'. If required to deliver water at 'normal' (60C-plus) rad temp, heat pumps' CoP suffers badly. So are we saying that PVT, or Agiba in particulasr, can overcome that CoP problem in a hard-to-insulate house?
    • CommentAuthorowlman
    • CommentTime5 days ago
     
    I can see the logic of keeping the panels cooler with its HW spin off, but I do wonder if its over complicating things.
    The downside, as with all Solar PV and ST in the UK, especially in the North, is its inability to produce enough, of whatever it does, during the depths of the winter heating season, unless of course you've got loads of it.
    IMO, by all means max out the straightforward solar PV, but then keep it simple and use its output to supplement the running of an ASHP, and/or immersion heater. What is the point of a sea of DHW in the middle of Summer.
  4.  
    AIUI the combination PV/thermal panels have been around for a while but haven't taken off because the demand for heating doesn't usually coincide with strong sunshine.

    Just about any house will benefit from a heatpump now, in carbon terms. Even if it has to run radiators at >60deg for a few days in midwinter with resistance top-up, there will be compensating benefits during all of the other milder months of the heating season, when the radiators can happily run cooler. This is expressed as the Seasonal Performance Factor SPF, which is derived from the CoP but corrected for the fact that only a very few days of the total heating season are -5degC.

    This has the double benefit that the heatpump CoP is better in milder air temperatures (expressed as the SCoP which you can look up) and the house CH can run cooler in milder months. These are combined to calculate the average SPF over the whole heating season.

    So long as the SPF is >1 (which it invariably is, usually >3) the heatpump is greener than electric-resistance, which itself is now greener than gas.

    Whether it is cheaper, is a different matter....
  5.  
    Tom, the other trick is that many older houses have the old style radiators, single panel, or double without fins. If you swap out the old style radiators for modern radiators the same dimensions, double with fins, you get twice or more the heat emitting area without paying to alter the plumbing, so can run the CH cooler. Worth doing even if replacing with a condensing boiler which needs to be below 50deg-ish to condense well.
    • CommentAuthorowlman
    • CommentTime5 days ago
     
    Tom, out of curiosity, why the emphasis on A2W systems in your client discussions. Is it the potential for RHI, or something else?
    • CommentAuthorShevek
    • CommentTime5 days ago edited
     
    Came across this pretty neat system the other day, which combines solar hot water + heat pump technology. I prefer this idea to PV + heat pump.

    No ducts. No ventilators that help evaporation process. No defrost cycles. Primary circuit does not need to dissipate excess heat on hotter days. You can also feed the cylinder with backup mains electric, PV, boilers, heat pumps, heat exchangers, solar collectors.

    https://www.energie.pt/en/solar-thermodynamic

    Edit: made in Portugal but also operate in the UK:
    https://www.energie.co.uk/products/index.html
    •  
      CommentAuthordjh
    • CommentTime5 days ago
     
    The key point of the Agiba system as I understand it is not so much the PVT panels as the seasonal heat store - warm earth under the foundations powered by and extracted from using a heat pump. Similar to ICAX that we've discussed on here before.
  6.  
    Posted By: ShevekCame across this pretty neat system the other day, which combines solar hot water + heat pump technology. I prefer this idea to PV + heat pump.

    No ducts. No ventilators that help evaporation process. No defrost cycles. Primary circuit does not need to dissipate excess heat on hotter days. You can also feed the cylinder with backup mains electric, PV, boilers, heat pumps, heat exchangers, solar collectors.

    https://www.energie.pt/en/solar-thermodynamic" rel="nofollow" >https://www.energie.pt/en/solar-thermodynamic

    Edit: made in Portugal but also operate in the UK:
    https://www.energie.co.uk/products/index.html" rel="nofollow" >https://www.energie.co.uk/products/index.html


    This is similar to my thinking of the solar thermal being linked direct to a water/water heat pump just going one stage further and replacing the solar thermal panel with the agiba type 2 power panels (PVT) It would still allow a top up of heat in the depths of winter from my existing biomass boiler but for the majority of the year would provide all heating, hot water and electric.
  7.  
    Posted By: djhThe key point of the Agiba system as I understand it is not so much the PVT panels as the seasonal heat store - warm earth under the foundations powered by and extracted from using a heat pump. Similar to ICAX that we've discussed on here before.


    Was not looking at that aspect or going down that route. Just looking at PVT panels providing a heat source for a water to water heat pump. I have a welsh slate roof and the slightest rays of sunshine it gets very warm.
    •  
      CommentAuthorfostertom
    • CommentTime5 days ago
     
    Posted By: owlmanTom, out of curiosity, why the emphasis on A2W systems in your client discussions. Is it the potential for RHI, or something else?
    Not RHI, just what's an alternative to the existing fairly recent gas combi, in a hard to insulate house (Listed Victorian 3-storey terrace town house)? We are doing roof and limited wall insulation which I guess will reduce heating demand by 40%.

    Another avenue was latest-tech electric storage heaters plus smart meter and half-hour variable demand-pricing tariff, with clever software to cherry-pick best tariffs at any time of day or night. But the whole point of smart metering is to eventually even out demand swings on the grid, so hi-lo tariff differences to cherry-pick will even out too.

    I also asked the forum if there's any kind of consultant who could advise on such cutting-edge strategies - I feel out of my depth to advise.

    Posted By: WillInAberdeenTom, the other trick is that many older houses have the old style radiators, single panel, or double without fins. If you swap out the old style radiators for modern radiators the same dimensions, double with fins, you get twice or more the heat emitting area without paying to alter the plumbing, so can run the CH cooler
    The house has recent cast iron 'hospital' rads - I guess they're quite high on output per frontal area already?
    • CommentAuthorowlman
    • CommentTime5 days ago
     
    @ Tom; What piqued my interest was the fact that you seemingly hadn't offered them, the clients, the option of A2A. Its relatively cheap, efficient,- better COPs than A2W, fairly simple to understand and install, and trouble free.
    It doesn't come with all the extras baggage of A2W and if RHI isn't part of the equation why complicate things.
    •  
      CommentAuthordjh
    • CommentTime5 days ago
     
    Posted By: fostertomBut the whole point of smart metering is to eventually even out demand swings on the grid, so hi-lo tariff differences to cherry-pick will even out too.

    Well no, because it is the different pricing that gives motivation to provide the balancing, so yes there may be some reduction but it certainly won't even out.
  8.  
    >>>"hospital radiators"

    You'd have to check the data of their particular radiator, but this one:

    https://www.screwfix.com/p/arroll-4-column-cast-iron-radiator-660-x-874mm-black-3726btu/8415f

    Has only 65% as much output as this double fins one, similar dimensions

    https://www.screwfix.com/p/stelrad-accord-compact-type-22-double-panel-double-convector-radiator-700-x-900mm-white-5797btu/170hx

    Not sure what your client would feel about that... but it would work with cooler CH !
    •  
      CommentAuthorfostertom
    • CommentTime5 days ago
     
    Thanks Will.
    owlman, will think about warm-air heating but doubt it somehow.
    I see hi-tech storage rads are bl**dy expensive - not 'the cheap option' as was.
    •  
      CommentAuthordjh
    • CommentTime4 days ago
     
    Posted By: fostertomI see hi-tech storage rads are bl**dy expensive - not 'the cheap option' as was.

    I don't understand them or their pricing. I think it's just 'fashion' pricing. I can't see how old-fashioned storage heaters and a 'smart' control system wouldn't do the same thing.
  9.  
    The ones I have seen, which were eye-wateringly expensive, were very slim, thus (one assumes) having 'fewer bricks' and thus less storage capacity, but with a fancy-looking (for which, in my case, read practically incomprehensible) controller. Trawling through the reams of instructions the 'USP' seemed to be that improved control would make them cheaper to run. Take this to its logical conclusion and I can make any electric heater zero-running-cost. (In fact there's one in front of me now).

    I won't be in a rush to buy any.
    •  
      CommentAuthorfostertom
    • CommentTime4 days ago edited
     
    Posted By: djhI can't see how old-fashioned storage heaters and a 'smart' control system wouldn't do the same thing
    And a lot easier to hack with the kind of AI I had in mind, 2 posts earlier. But prob the heat-storage density, retention/insulation and regulable output will be significantly improved over the 'old-fashioned'. Or not - what do we think?
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