First in a series seeking free advice for my upcoming refurb project
So, about six weeks have passed since I moved into my Tooting pile, if that expression doesn’t sound somewhat 
inappropriate. A month and a half of doing the easy, if still sweat inducing, stuff. Pulling up, ripping or steaming off or smashing into smithereens. Yes a lot of this is quite fun. But things are about to get a bit harder. Plans to be considered and then decided, cold hard cash to be spent and a deadline of three to four months to be met. Yes we’re about to meet the inevitable crashing of dreams, ideas and nice notion into cold (yes it has been quite chilly in here) hard reality. That rather snazzy PV/ground source/solar thermal system is literally days away from being firmly crossed off the cost plan. Oh well, it was nice while it lasted.I’m being flippant. After all eco-frippery was never really on the cards for us to start with. When all the basics are needed you can’t sod around the edges. There’s some form of central heating to be fitted, electrical wiring that needs to be brought into the second half of the 20th century and walls and ceilings to be saved from crumbling to the floor before more ambitious plans are sought.
But I’m clearly aware at this stage of key decisions to be made. So in the spirit of the giving open and generous internet that all the smart-arse books I read tell me it is I’m seeking consultancy on the cheap. And in the spirit of Radio 4’s Gardner’s Question Time that falls on the Sabbath, here I am with the Refurbishment Question Time (just in time):
- Under floor heating – worth it? It tends to be done on: new build; with a concrete pour. So how feasible is it on: refurbishment; and with wooden floor boards? Clearly the walls will need seeing to but underfloor heating seems to me a great option, especially as our house has no central heating in the first place. We have an open book. Unfortunately, and inevitable, we don’t have an open cheque book either so I’ll have to see the figures before plumping for it. Interesting to get views on the for or against of under-floor.
- Do we allow for solar thermal?: We’re pretty certain that solar thermal is great but not realistic on our current budget. So do we pay a little more and allow for it to be slotted in retrospectively (ie. piping and cylinder)? Will future solar thermal systems be both more affordable and more efficient?
- Grants? I’ve looked around but wonder whether it’s worth the effort, given the bureaucracy you have to go through and the limited cash available. Any hidden stashes of green funds I can get my hands on.
There’s plenty more where those came from. I’m thinking of some really exciting (and cheap) presents for those that provide the best answers.
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on Jun 15th, 2009 at 10:43 am
Phil,
UFH? Possibly on the ground floor only, but only if you are lifted the boards to insulate underneath – which is possibly a better idea than UFH itself.
Solar thermal ready. Why not – invest in a dual coil tank at least.
Grants – unless Tooting has something special for it, it’s unlikely to be worth it. But wait and see what Feed in Tariffs have in store next year.
on Jun 15th, 2009 at 11:58 am
I’m moving to Tooting too. The prospective properties has all stripped wood flooring and sash windows. All very pretty, but I imagine my bills are going to skyrocket compared to the mid-floor 70s council block with newish double glazing I currently reside in.
on Jun 15th, 2009 at 3:56 pm
1. Phil, pleanty of evidence for the cost benefits of underfloor which can be hung in trays between joists. Benefits are obvious from improved living environment, energy and carbon savings (it runs at 35c) but it really depends on how much work you’re willing to do!
2. Solar thermal really is a no brainer provided you have a substancially south facing surface to mount your panels. If you can’t afford it now then definately install a solar cylinder and buy later but don’t expect big price reductions, it’s already done that!
3. Grants, not at the moment but watch out for potential news regarding the Low Carbon Buildings Programme. Some manufacturers are offering incentives to encourage renewable installations.
4. Spend as much as you can on insulation, air tightness and efficient glazing.
5. Get a copy of our Sustainable Products catalogue!
on Jun 15th, 2009 at 5:52 pm
Mark – yes I think it may well be ground floor only. A heating guy said a dual coil tank would costs around £400. Does that sound right?
Colm – welcome to Tooting. It’s very friendly down here. The curries are good as well
Tim – Just ordered one of your catalogues. Am keen to progress with UFH but we’ll see how the numbers come up
on Jun 18th, 2009 at 1:23 pm
Phil,
Underfloor Heating:-
Underfloor heating for space heating may be seen as a suitable heating solution in an older house where it is difficult to install alternative heating systems, e.g. install build difficulties, cost and risk of heat loss through the building fabric, for example through external perimeter walling where using mounted heating if there is no external wall insulation.
However whatever mode of heating is used – even Underfloor, it is a priority to insulate the building fabric to reduce heat losses which will still exist with its use; the easier practical and cost solution roof voids followed by walls etc… Roof voids can normally be fairly straightforward, with loose-fill, blown or semi-rigid or rigid insulation. Walls can be a bit more challenging as this typically might involve dry lining with semi-rigid or rigid insulation within it or surface mounted. This may impinge on internal space losses and constructional complications around window door openings.
Other areas of heat loss are through the windows which can be addressed, if required, but typically at significant cost, i.e. with replacement. And additionally through floor levels which can be addressed through insulation between joists and at ground level which is a more complicated challenge, even non-feasible where flooring has to be removed and modified such as a ground floor slab.
Other methods of prevention with ‘air & heat leaks’ i.e. draught-proofing around openings and apertures can be undertaken with excluders, sealing strips and brushes etc…
In all instances of insulating, draught-proofing and subsequent change of heating and building occupancy and use, care must be taken, particularly as if the building is established such as being ‘of age’ e.g. ‘traditional’, it’s nature, behavior and performance can be suddenly changed, and there are potential risks such as giving rise to issues with damp – interstitial condensation, dry rot, mould etc.. where air flow and breathability of building materials which may once have existed is interfered with, together with changes in ventilation; Baubiologie (Building Biology) the quality of indoor environments, the interaction of Hazardous building materials – dust particles, fibres, radiation and volatility of compounds, and SBS (Sick Building Syndrome), through release of substances – toxins etc… from building materials and products. There has been some commentary regarding the pitfalls of poor ventilation in buildings and health effects to occupants on blog sites and on Twitter. It must be stressed, consideration to the ventilating the building structure and fabric is additionally as important, to prevent building defects.
Care must be taken with the use of any insulation/draught-proofing that consideration is given to any interaction with damp that may occur to prevent it’s possible degrading or rotting, i.e. it is lined with say foil, or treated/coated.
With Underfloor heating 3 points can be considered and addressed with its use.
1.
You don’t have an Aladdin’s cave in your house with fittings and fixtures; otherwise you will be heating the underside of furniture and the like and not the room space.
2.
You consider and address potential heat losses beneath the level of where the floor heating will go, otherwise these will occur at this point before any heat is radiated to occupancy levels, and the challenges of reduction and prevention out through other parts of the building fabric.
3.
The floor structure and finish it is to be fitted within, to get maximum performance e.g. heat transmittance in the right direction, and the right amounts – with issues and relationship such as is it to be fitted within or over joists, or a floor slab etc. And additionally without damaging any materials; there is mixed debate on such a subject e.g. warping of wood flooring, and ensuring it has the right treatment such as being kiln-dried. However it might be a case of having to do with, work with and build around what materials are already there, so consideration has to be given to how any such materials might behave, when their environment suddenly changes. If they are aged, it might be deemed they have already weathered/settled, e.g. moisture content; sufficiently enough not to warrant such possible damage.
Solar Thermal Heating:-
By solar thermal, the assumption is with use of solar water heating (solar thermal itself is a broad definition in crude terms encompassing the use of converting solar sunlight or energy into heat, through or via a medium – a material mass, water/fluid or air, with techniques including thermal mass, water heating etc..).
The technology for solar water heating and its use has existed for some time with potential – compared with what can be seen Photovoltaic’s for generating electricity, there can be identified greater productivity and efficiency with lower installation costs and thus payback return.
Key factors tied in with obstacles to use are:-
- Cost
- Appearance
- Performance
- Reliability and maintenance.
It is important to ensure a building to which they are directly used, has no interference, or obstructions, e.g. overhangs with say shadowing from other buildings, trees, landscaping etc…
A building with ‘Solar aspect’ surfaces to fix or mount a system to, in order to see the sun all year round, is imperative to maximize performance. Understanding solar geometry with apparent path of the sun is important (through use of sun path diagrams) both on horizontal (polar diagrams) and vertical planes (Cylindrical projection with altitude & azimuth angles, as indicated in a Waldren diagram). A directly south aspect maximizes solar gains, though not always available, the next best thing is a general southerly aspect, i.e. south-east, south-west. Other aspects can be used, though performance through lack of solar energy can seriously be reduced. An inclination angle of a degree can also make a difference with performance (for highest efficiency, an angle to the horizon equal to the latitude plus about 10 degrees is typically recommended as the optimum orientation).
Solar energy exists in 2 forms: Direct (non-interfered / non-deviating beam) & Diffuse (absorbed, scattered or reflected solar beams through changes in colour of sky, or through interference, e.g. cloudiness or overcast, water, aerosols, pollution, dust haze etc..) sunlight. A system will work at its best with direct sunlight or radiation and ultimately combination of both (being global solar radiation or total intensity). A common myth is that they function only under direct radiation. They can perform to a certain degree under diffuse sunlight or radiation but depending on such periods (e.g. length) performance can be reduced to even poor. With technological improvements these performance factors and issues are continually improving.
Evacuated tubes compared with Flat Plate Collectors are often portrayed and demonstrated with common consensus as having better performance with higher generated temperatures and efficiency, performing better with variations of both direct and diffuse radiation, and being seen to perform better with weaker solar energy, thus particularly suited to cooler, cloudier climates (in short: eliminating of convection due to vacuum in the tubes minimizing heat loss), being further improved with ‘direct’ evacuated solar tubes (no antifreeze). The cylindrical shape of the tubes means that they are always in direct contact (perpendicular) to receiving the suns movement at different points to them during most times of the day. Their advantage is largely lost though with warmer climatic conditions, where resulting water can be too hot for required use when not wanted – thus over performance.
Flat Plate Solar Collectors can produce similar heat output to evacuated tube collectors; they do have a larger absorber surface area to absorb solar energy, but due to the conceptual nature of design are at risk of also re-emitting the heat – they generally perform well with good consistent levels of solar energy e.g. during warm, still, sunny conditions. Thus, they are well suited to sunnier climates. Unfortunately with their large flat surface area, maximum energy is received only when the sun is directly concentrated (perpendicular) to them, with its movement, this is at noon.
When averaged over an entire year, Evacuated Tube Collector heat output per net m2 of absorber area, can be as commonly quoted, in the range of 25% to 40% greater that a Flat Plate Collector.
Evacuated Tubes are more expensive than Flat plate solar collectors. The odd tube can fail over time, though only the damaged one needs replacement. With damage to a Flat Plate Collector panel, the whole unit may or more than likely need replacement.
However with peak efficiency (maximum solar gains e.g. summer) it might be deemed that there is little to difference between Evacuated Tubes and Flat Plate Collectors. Averaged over a year, Evacuated Tubes are typically seen to have the better performance with efficiency.
Different tests on 8 collector solutions: 2 Evacuated Tubes and 6 flat plate, carried out by the UK Department Trade and Industry (DTI) concluded evacuated tubes coming out ahead of Flat Plates.
There is debate and argument that performance with efficiency is generally not as identified and that it is the other way around, with Flat Plate Solar Collectors being better performers than Evacuated Tubes. The DTI tests can be said not to have been comprehensive enough with variety of examined solutions, other tests have been highlighted and pointed to, such as with the research organisation Solartechnik Prufung Forschung (SPF) which on the other hand tested over 160 solutions of both types, concluding better overall performance and gross average efficiency of all the Flat Plate Solar Collectors over the Evacuated Tube counterparts.
Flat plate solar collectors are currently the more common choice for solar water heating. They are better suited to meeting aesthetics requirements, being a regular smooth surface with what might be seen as tolerable profile depth – less obtrusive, blending in better with a building surface e.g. roof, rather than evacuated tubes with irregular shaping and profile making a ‘chunkier’ bolder statement. As a result planning requirements may dictate Flat plate collector use with say listed building / conservation areas. The often seen greater efficiency of Evacuated Tubes compared to Flat Plate Collectors can be a benefit, with the potential requirement for using fewer units and less roof area being covered.
With any product whether Underfloor heating or Solar Water Heating there are good and bad, end useable solutions. For example, there are good flat plate collectors that may perform better than poor evacuated tubes say in colder climates. And other contributing factors are how these solutions are actually used with design for user demands requirements e.g. capacity/delivery, and how they are built into a building and integrated with other systems, and building elements. For example, the final performance of Solar Water Heating also depends on the design of the whole Solar Heater System – issues as the pump consumption, controller, or hot water cylinder location are important.
Through continuing technical developments such as with say, as an example, making use of solar energy and resulting solutions, with better solar energy absorption materials e.g. selective surfaces, insulation etc… there is scope for improvement with performance and economical factors, such as efficiency, installation, maintenance and running and payback costs.
When considering for use an end-user solution such as a product, it is always important to get as much information as possible, not just through the manufacturer, supplier or installer with say technical information, and tests for example , but independently, from un-bias sources, together with precedence, case-studies, example installations and build work etc… and where possible with comments of users. Accommodating companies and trades people should be able to supply such contacts and references.
Grants:-
What might be seen to be available and what can actually be got, is a real grey area. Insulating a building such as roofs and cavity walls is more likely attainable, as it’s to do with reducing CO2 emissions (a ‘save the planet’ plus), but what might be seen as fancy gadgets or optional extras, e.g. solar panels for water heating or generating electricity, or even space heating which might be seen as a comfort requirement can be much more difficult to obtain for, but it’s all worth pursuing.
The priority of worldwide governments is about reduction of CO2 emissions. Finite resource use is somewhat bizarrely behind on the radar, and yet with solar panels, these afford the opportunity to lessen dependence on fossil fuels, oil, coal, gas etc… – the traditional forms heat & electricity generating.
As a last point of interest, in the days of grants for converting cars to run on LPG, the percentage of people who applied and successfully got the grants was laughable.
on Jun 18th, 2009 at 1:58 pm
Robin. I’m digitally speechless at the comprehensiveness of this response. When I asked for free advice I wasn’t expecting such a fantastic guidance note. Need some time to take all this in. You’re my new hero Robin.
on Jun 22nd, 2009 at 7:18 am
Phil,
The amount you spend on a cylinder depends on the performance you want re insukation, recovery time and whether or not its mains pressure. A second coil is a marginal extra.
Have you come across http://www.parityprojects.com. They are in Sutton and might be able to help.
on Jun 26th, 2009 at 6:51 am
Thanks Mark. Have been in contact with them in terms of an energy survey.