Hear from an expert on the ins and outs of solar systems to generate electricity and to heat water, and heat pumps to replace gas boilers. It can be difficult to get reliable information and good advice, and this talk will be of value for anyone who is considering such an installation, or just wants to understand more about home generation and heat pumps.
The talk and questions will be from 7.30pm to 8.30pm and there will be a chance to continue discussion and questions afterwards over refreshments. The talk will be in person and live streamed. The livestream link will be sent to ticketholders in advance.
Kaspar has been working in the field of heating and renewables for 8 years. He studied mechanical engineering and renewable energy systems at Dundee University. He worked as a Solar Thermal Engineer installing solar hot water systems. He later went on to work in Ghana, West Africa, where he installed gridtied and stand-alone solar PV systems. Kaspar worked at Enhabit managing the design and installation of MVHR, Heat Pump and Solar projects. He continues to co-ordinate this work at Next Step Heating.
Yes e it’s hello good evening welcome thank you very much for coming this is the penultimate event of of uh muswell Hills sustainability group’s green Open Homes program um we’ve been running the program for 10 years now this is the 10th year and I wanted to read to you a
Short quote which I think is quite good at uh summing up why we’re doing this um and what the thinking is behind the green Open Homes it’s a quote from Howard Zin got to take my glasses off at this stage and if we do act in however small
Away we don’t have to wait for some Grand utopian future the future is an infinite succession of presence and to live now as we think human beings should live in Defiance of all that is bad around us is itself a marvelous Victory so what I’d like to do is to uh
Introduce Casper Bradshaw and thank him very much indeed for giving up his time to talk to us this evening I have uh a personal professional connection with Casper in that he was responsible for helping me put a solar thermal system on my own house and he did a great job
Since then his name keeps cropping up with uh the warmest references you could imagine from Architects that we uh have connections with who are very knowledgeable about Eco building and particularly the Eco retrofit um and he’s going to talk to us this evening about solar thermal solar
PV and heat pumps and I think he’s going to squeeze in a little reference to temperature compensated Control Systems um so I will uh hand over and I think you can use that mic y thank you thank you very much Jeremy thank you everybody for having me today it’s great
To be here um with the muswell hill sustainability group uh so my name is Casper and um just a little bit of introduction about me I went to Scotland to University to study renewable energy uh with the focus of mechanical engineering I learned a lot about wind
Turbines um I was able to go to Germany for a year as part of the Erasmus program which is no longer sadly operating and I learned a lot in Germany about renewable energ about solar panels and when I came back from there I then worked in London installing solar panels
With a local company here so I actually got some experience on the roof using tools doing Plumbing work and um from there I then went to another company called inhabits where I worked for five years organizing U this kind of work the kind of services installation of solar
Systems and um heat pumps and also mvhr ventilation and then in the last two years I’ve been running my own company Next Step heating doing the same sort of thing as well so um I’ve had the the fortunate um luck to be able to work in the field that I studied
You know it’s quite unusual that you can actually study something you’re really passionate about and then actually day to day do that as well so um it’s been an amazingly um you know enjoyable kind of period of time and I’ve also had the opportunity as well to do a lot of
Experimentation so I’ve been able to work on projects that are pushing the boundaries trying different things out and I’ve learned a lot through that um one thing that I really brought me to work in this field of the domestic sector Renewables is that the projects are quite short they’re quite a short
Space of time in terms of the involvement with the engineering kind of side and what that means is compared to for example a hydroelectric Dam which takes 10 years to build the short projects mean that you learn a lot you make mistakes and you learn from them
And very quickly you can you can actually have quite a lot of experience because you’ve done some you’ve seen what happens and you’ve been able to keep improving so that’s something that I do like about um you know in being in the domestic sector So today we’re going
To talk a little bit about Renewables about heat pumps heat pumps are for domestic construction industry quite a relatively new development and all of this new development links back to the changes we’ve had with renewable energy generation which is wind turbines I’ve had a huge growth in the in and
Production with we’ll talk about that later and so because they’re relatively new on the scene there’s obviously lots of questions there’s lots of um uh there’s quite a lack of knowledge generally in in the kind of people you normally rely on normally you reply on your plumber to tell you the best thing
To do for your house in terms of heating in terms of hot water and now with this as there are less plumbers that are experienced it becomes more difficult to get good advice you know sometimes you feel like maybe they’re telling me to keep a gas spiler because that’s all
They’re confident that’s all they know about so sometimes it can be sadly now a bit more difficult but um the number people is growing who are able to to work with heat pumps so hopefully it is getting easier to to get good advice so um let’s jump into the
Presentation um these are some of the things we can look at so the first thing is how does the heat pump work a little bit of physics so basically the heat pump is moving Heat essentially so it’s using something called the refrigeration cycle if we go to the next one U and the
Refrigeration cycle is quite clever it’s quite physics based and it all comes to this thing called the refrigerant so the refrigerant is basically a gas that U melts at very low temperatures so at minus degrees it can it can undergo a phase change from gas to liquid um normally we think of water
Boiling at 100° but this refrigerant can actually boil at minus temperatures very very low temperatures so what we can do is we can force that refrigerant around a mechanical um circuit and we can make it expand into gas and then contract back into liquid and as it does those
Phase changes it either releases lots of energy or absorbs lots of energy so you take that change and you put it into a mechanical system either one that’s got a heat exchange with lots of air blowing through or a wet heat exchanger and you have your heat pump and the good thing
About this system is the electricity that it uses in the compressor to actually drive the gas around the system is a lot less energy than the amount of heat that we can transfer from one place to another place and typically we talk about roughly 300% efficiency so you can
Um compare to a direct Electric radiator you can have a lot more heat um compared to how much electricity you used to run the system so that’s kind of the basic um reason why heat pumps are preferable um heating system in in um in these kind of
Situations and um the big um the big change that we’ve had is this all this thing going back to the grid the reason why heat pumps are now um being funded by the government you’re talking uh recently it’s the funding has gone up from £5,000 to £75,000
Funding so it’s quite significant so you have to ask yourself what is the background to this why is the government so Keen to push heat pumps for 50 years we’ve been using gas spoilers how why now is the heat pump so you know uh popular because heat pumps are not a new
Technology they’ve been around for 50 years we’ve had heat pumps just as long as we’ve had gas boilers so why are they now becoming so popular and it all goes back to the um increase in generation in the grid so if you look at this graph here
What you can see is the coal is an orange so the coal generation in the UK has really tapered down over the last 20 years and you can see um the the the flip side of that is the dark brown on the bottom is actually bioenergy and slightly debatable here
Some of the coal stations have literally just switched over to biomass and are still relatively polluting um it’s quite a controversial thing at the moment what they did is the UK actually made up some of the criteria for biomass and made it look very green to begin
With but now we’re having to review that and go back and say actually is it that green to be importing wood on Mass from Canada from Russia to useing what used to be an enormous cold fire station where there isn’t local heat being utilized it’s just for electricity so
That’s that’s obvious a little bit of a cash uh more controversial side but the the positive side is the light blue there which is a huge growth in wind generation and that’s about um gone from being um 2% to 20% 2018 and during lockdown we even had 50% of electricity
Was coming from wind wind power in the UK so during lockdown our electricity consumption went down and we were really using a lot of wind energy so the UK also in Europe is one of the few countries that actually has the most capacity to increase even more its wind
Generation because of the amount of Coastline we have in the UK we’ve got so much Coastline that we could actually be exporting wind power back to U the continent and to the other countries where we’ve got um power lines connected to so there’s much more potential going
Forward for us to have even more renewable energy Generation Um so because of this change this is what’s changed the numbers on what’s the most efficient way to uh use energy for heating and um if we go back to this one here we’re looking at the efficiency of
Different types of systems so when you make electricity if you’re using coal you’ve got to transport the electricity from the Power Station to the house there are losses everywhere but as that coal is being replaced by wind power the carbon the carbon um concentration of the grid El electricity comes down and using
Electricity becomes Greener and it’s got to the point now where using electricity is direct electricity is about the same carbon um energy operational energ use as using gas and so if we’ use the heat pump as well uh and the refrigeration um efficiency we get even bigger carbon
Savings so the the the the back to the first question again why they so popular is because nearly every model that’s been made from climate predictions going forward how are we going to uh reduce our carbon emissions they all rely on changing over to heat pumps heat pumps
Are a really big part of the Strategic uh models that have been made for reducing our carbon emissions so that’s the background to the heat pumps um but the reality is uh that there are some obviously some limitations and some challenges with doing that in practice it’s all well and
Good having the theory but how do we then go and do it particularly in London so the first challenge is this graph which I find very interesting and at the bottom in white is our current electricity usage and the red is if we took all of
Our heating energy in the UK and we just switched it straight to electric heating so if everybody just bought cheap fan heaters from the shop and just heated their houses with electric radiators how much electricity would we need and you can see that between the white small
Little lines of to the bottom in the red is an enormous increase in energy would be needed if we just straight away everyone just starts using electric electricity and the um the Blue Line further down is a combination of heat pumps and also some energy storage so
You can see that with the heat pumps we can significantly reduce that burden from the grid of how much electricity we need to draw because the grid obviously has a limited amount of electricity that can travel across the country um the grid was made during um after the war
And that was a huge investment took a lot of money to build it in the first place increasing it to twice a capacity three times a c capacity is again a huge infrastructure challenge so anything we can do to reduce that burden on the grid is um going to be a much more
Sustainable way to actually get to the goals we need to get to and it’s very important as well to say that because of this what this graph illustrates is we’ll only really get to a um Net Zero or low energy economy in the UK If we also consider fabric first approach
Which is insulation which is reducing energy use to begin with so if we have a building that’s got single glaze Windows that’s got solid brick walls with no insulation those are the things we should be thinking about first are there ways we can add insulation the ways we
Can change the windows the air leakages all of those aspects um we need to take that into account to on on a kind of national strategic level to be able to realistically be able to heat all our homes using electricity so if you look at heat pumps
Um is a very confusing area because it’s quite versatile the heat pump technology the the refrigeration cycle it’s quite versatile we can do different things with it so traditionally what we’ve seen a lot of heat pumps being used for is what we call called air conditioning AC
Systems so you’ve got here on the right hand side AC systems now typically used to provide space heating or space cooling because only the air conditioning system is actually able to give you cooling because with cooling you need to have cold air being blown around to quickly make people feel cool
So that is how we know really heat pumps in the UK through air to- a system they’re called air to- a because it’s is taking energy from the air outside and then it’s delivering that energy again via the air so the medium of heat transfer is both in the air to air with
The heat pumps that we’re mainly talking about and the government is actually subsidizing is called air to water so the heat exchange on the outside is with a heat exchange with fins and a fan blowing air through it and on the inside we’re using a central wet heating system
That could be radiators could be underfloor Heating and it can also heat a hot water tank a stored hot water tank again with wet Loops that go inside to heat it up so very similar terms here air to water air to Air and yet it’s got very big implications in the actual
Industry the air to AAR is our air conditioning units uh no Government funding for them the efficiency of the two systems is very similar they’re both very efficient they’re both very good ways of reducing energy use if you’ve got like for example this building here if we had previously electric heating we
Wanted to quickly make it less energy efficient it might be cheaper to put air conditioning than to install lots of Radiators and air to water heat pump because of the level of in infrastructure pip workk that would be needed for an air to water system
Compared to the air to air so air to air can have some very good um uh applications the issue for the government is that because people use it for cooling they don’t want to substance idiz cooling they don’t want to subsidize people actually just have it for Comfort cooling which is an increase
In your energy consumption to do Comfort cooling um and you can see there there’s some pictures there of the the different heat emitters so different types of heat pump we talked obviously about the kind of air source heat pump using the air as a source but there are different ones as
Well we got the uh closed loop Lake collector so there are some heat pumps that actually get the heat from the the temps River there are some installed Upstream some in Oxford some in the upper levels of the temps that have pipes that go into the temps and they
Actually make the water a little bit cooler and use that to heat their homes now there’s some implications on that one is impact on the environment impact on Aquatic Life you have to have some surveys to assess the level of water flow what impact would that have on the
Water temperature there are some buildings historic buildings um that you see that have the similar thing as well air to water um heat pumps and the good thing about the water is it doesn’t get as cold in the winter so the issue with the air to- air system is in the winter
The air drops to quite a low temperature water and the ground doesn’t get that cold the ground only gets to about 12° minimum about a meter depth below the ground it only gets about 12° so it’s much warmer than the Ambient Air Temperature and um that’s another one
People are familiar with the the ground Source heat pump that one needs the closed ball Loop uh is one example where you have a ball hole very very deep um to use it in London is very expensive you’re talking about 20,000 extra cost minimum just for the B holes so looking
At kind of that kind of system it’s a very big and the saving you’ll get from that rarely eats into that initial cost doing ground Source heat pump systems youve got to look at uh a survey of the underground infrastructure drainage services in some cases even people have drilled into the train underground
Tunneling putting in ground heat pum it’s actually happened there’s photos of it um and the other thing also you got to look for unexploded bombs there’s a survey in London of where unexploded bombs may be um because from World War II that’s another thing that’s of concern and there’s also actually secret
Tunnels under the London used by MI5 that we don’t publicly know about but you can gain you can have a rough idea when you see access points that are not labeled for any purpose that again is an indication that they may be used by MI5 so there’s there’s a lot of things to
Look into for people doing this ground source and there are some people who do it more commonly it’s done outskirts of London where you’ve got a large field a large patch of earth needs to be at least about an acre size we’re talking about a big amount of land where you can
Basically dig up the whole thing with a tractor and lay coils of pipe in the ground which is much cheaper to do than the ball hole system and um gives you much better efficiency talking more like 400% efficiency compared to the airs Source system so um that’s good we’ve
Got another one here solar assisted heat pump that solar sisted heat pump is a bit more Niche and the way to think of it is it’s very similar to solar thermal it’s almost the same application as solar thermal systems so with a solar assisted heat pump you’ve got um a panel
On on the roof with refrigerant pipes inside when the Sun Shines on that refrigerant panel and the heat pump starts working you get very high efficiencies 800 900% efficiency because there’s so much sun energy going onto that panel when the sun doesn’t shine it’s pretty much useless because using a
Panel is not an effective way to when there’s no sunshine is not an effective way to move heat around you really need air and you need an air exchanger to move a lot of energy and when there when there’s smaller temperature differences so the solar assisted systems is
Typically in addition to another backup heating system used generally just to sub subsidize um hot water because hot water is something you need in the summer summer and sunshine go together well so a bit of background on that one you’ve got the exhaust a heat pump so
The exhauster heat pump is a bit of a compromise and it works with something the ventilation system so you might have a house whole house ventilation Sy system it’s bringing air in from outside into the bedrooms into the living room it’s taking air from the bathrooms and
The kitchen back outside and with the exhaust a heat pump we use that air flow of cold air from the heat exchanger to outside we use that to make it even colder and then provide some additional heat it can either be to heat a hot water tank give some hot water heating
Or it can be a little bit of air transferred heat space heating the problem with the ex exhauster heat pumps is that an mvhr system this ventilation system works at about maximum half an air change an hour maybe generally more like a third um air changes per hour so
Quite a low level of of air flow rate in order to move heat for the air source heat pump you’re talking about 8 to 10 times higher flow rates so you need a lot of air flow to really move a meaningful amount of heat to really do
Something with and this is the reason why the exhaust heat pump is more of a compromise if you haven’t got somewhere to put an outside heat pump system then if it’s like a block of flat something like that or it’s a building that hasn’t got any space then that can be an
Efficient way to provide hot water heating as well as the ventilation but it’s interesting to know about these other things because you hear lots of names you hear lots of Brands the brands always come out with amazing efficiency like the solar assisted came up with some amazing efficiency kind of claims
And then it took them to actually go and be tested uh independently for those claims to be a little bit kind of brought down to reality so um I think it’s always good to have a bit of a basic understanding what some of these other things are I haven’t talked about
The gas heat pump the gas heat pump is um is much lower scale uh in what you might see sometimes you have Camper vans you have a fridge a gas heat pump fridge where you put gas inside it burns the gas and it uses that to power the fridge
So um on a domestic scale generally it’s a much smaller smaller thing that you might see with that so that’s more about the exhaust a heat pump so what are the efficiencies with the heat pump system what do we want to think about when we’re thinking
About doing heat pumps so um you’ve got the kind of outside unit um you want that to be somewhere where there’s good air flow so sometimes people think let me hide it away I don’t want to see it it’s a very big piece of equipment let’s
Put it in a kind of kind of Hidden Away Courtyard space so I won’t see the problem is if it’s hidden away there won’t be also any air flow to it um one thing about the the air source heat pump is it’s producing cold air because we’re providing heating inside the building
And cold air doesn’t rise up like like hot air does and it won’t naturally want to go away it will just want to stay exactly where it is so for example if you put a heat pump down where the um the the the drums are over here and it
Was blowing against the wall over there that whole area would have a little microclimate it would be maybe four five six 7even 8 degrees colder than the rest of the room and the heat pump would be working much less efficiently and it might break every year because of working at such cold
Temperatures um so it’s something to be avoided you want it to be somewhere where as the heat pump blows a away from it that air will then be taken away and will get new air into the back of the heat pump so that’s always something to
Kind of Bear in mind something I explain to people as well is if you think about the volume of the house the volume of a whole house you’re trying to heat all of that air up inside that house that’s kind of the amount of air you got to
Think of passing through a heat pump and then getting away from the heat pump so you want to have it in somewhere that has generally we recommend to have it in a garden somewhere where it’s it’s exposed sometimes in the front of the front garden as well it can work
Sometimes depending on how big the front garden is um then we’ve got some other things as well so we’ve got um different types of heating underfloor Heating um times 8:00 um so yeah with a heat pump it’s it’s got limitations we talked about one limitation just now about the
Electricity grid so one big question is why can’t we just you know for every place where there’s a gas boiler why can’t we just take them all out and just put heat pumps everywhere like what’s the problem why can’t we just do that because we know that heat pumps are very
Efficient we know that the running cross are similar to gas boilers so apart from what we talked about earlier what are the other reasons so one of the things is that the actual power consumption of that heat pump so you can just keep buying heat pumps and keep making them
Bigger and bigger three-phase heat pump you can go up quite high power usage you can apply to the network operator say put me a new cable in just for my heat pump um but it becomes very expensive so the key thing then that you get to with
Heat pumps is well how much heat do you really actually need because if you don’t need that much heat there’s no point paying thousands and thousands for this enormous heat pump system that actually doesn’t need to be so enormous and so with the heat pump system because
We’re also trying to the fabric upgrades as well we’re trying to inate the building as well reduce the energy loss we can heat at something that’s called continuous heating so you’ve got something called intermittent Heating and continuous so with intermittent heat you might say like this hole for example
Let’s just let the hole completely cool down won’t do any Heating in here and then when we come back tomorrow at the same time 9:00 maybe a couple of hours before we’ll just heat the hole up again and that works okay for buildings that you’re not using most of the time but
With a house if you’re there for quite a long period of time particularly if it’s well insulated it can be much more efficient to let it stay closer to your target temperature and the reason if you do that as well you don’t need as much power to keep it at that temperature you
Can reduce how much power you need because you’re always topping up and keeping it close closer to your target temperature so an important part of this is the calculations that’s what this kind of picture here is the calculations how big are the walls how big are the floors the windows and previously to
This being a thing uh Plum has never had to do many calculations because with a gas boiler from the default you have a huge oversizing potential with a gas boiler it’s hard to make it small it’s hard to actually give some a gas boil spoiler with a low heat output because when you
Burn gas straight away you release loads of energy gas is an amazing I mean it’s taken millions of years to create gas under the ground you know centuries long uh processes so once you take that energy and you release it actually it’s loads of energy so some of the boilers
Um visman and and veent some of them with uh the con the modulation they have a gas valve modulation and it can actually close the gas valve to stop the gas coming so has a little bit gas coming in and they can take down the heat output quite low but that’s quite an
Expensive part of those gas boilers and the cheaper gas boilers don’t have as much regulation at the gas valve and they can’t go as low so what that means is when the gas Engineers come along they say well how big is the house let’s
Do 24 Kow let’s do 32 Kow let’s do 40 Kow and the difference in price between those different ratings is maybe just 200 difference so it’s a little value with the heat pump pump every 3 Kow of extra output is about 1,000 pound so it’s significant so the calculations
Suddenly become really important and that’s why you need to then kind of have a good survey a proper measurement and you need to also be thinking about insulation what’s the actual um the heat loss through that medium and what we find is with things like wall insulation
For example the first bit of insulation makes quite an enormous difference so an uninsulated solid brick wall may have a u value of two maybe one and a half to two a solid brick wall if you adjust 20 mil 50 mil of insulation you can bring
That down to. 5.6 which is half if not a third of that heat loss with just a quite a small amount of insulation so the the the impact of adding insulation is significant to the the implication the design for the heating system for how big the heat pump needs to be how
Big the radiators need to be um whether you’re going to get the house warm enough or not the pipe work that has to carry that heat around the house so um that’s obviously a big part of of doing the calculations we’ve got underfloor heating underfloor heating is
Good with heat pumps because it works at a low temperature the floor with a wooden floor you don’t want it to go above 27 de if you’ve got a wooden finish because if Timber floor goes above 27° it begins to warp it begins to change shape and if you see like some of
These old floors the tongue and groove floors not tongue and groove sorry the um parquet floors that have like Herring bone styles on them if they start to get too dry they can literally lift up and you’ve got a completely uneven surface and that can happen with any wooden
Floor it can start to deform and change shape if it gets too dry if the surface is too hot and it gets too dry so because of that under floor heating wants to be at a low temperature and low temperatures are great for heat pump efficiency on the downside with
Underfloor is they take a long time to respond so if you switch if this church had underfloor eating now and it was cold and we switched it on it might be two or three hours before it actually started to get warm and started to feel it in this church we’ve also got carpet
On the floor which is an insulator so when people put carpet and underfloor heating they’re actually the carpet is actually stopping the heat from getting out and uh means it has to work even hotter to give the same heat output so underfloor heating can be great but it can also compared to
Radiators it can also need more energy because it has to switch on earlier and it has to um has to stay on it has to be on for longer so depending obviously on the on the house depending on the way some people like to live always in a
Really warm house other people don’t mind putting on jumper and and slippers and being in cold houses and have it on people have got different kind of habits with heating and uh underlow eating is not one that you can switch on and off it’s not one that you can control in
That kind of way you’ve got to leave it for much longer time periods um but another good thing about it is it’s all plastic in under floor it’s all plastic pipe and plastic pipe doesn’t corrode like radiators do so you don’t get that gradual degradation so with radiators as
They get older you get more and more metal f l in the PIP workk everything gets a bit more Rusty and needs replacement so um these are some little graphs showing you efficiency so um what this one over here on the right hand side shows is that
When it gets warm outside heat pump is more efficient but sadly in the summer when it’s most efficient we don’t need any heating so um that’s bit of an inherent um reality with this the system um and that’s why we always talk about the seasonal coefficiency of performance
We’re always looking at how does it behave over the whole year as a whole not just taking one day here or there not just comparing and when you look at the data sheets sometimes and you see amazingly High figures that’s because that figure is taken at some specific
Operating um parameter that’s great if you look at the average whole year you then start to get much more realistic efficiency levels so this is something just about kind of customer uh awareness when you’re looking at different things when people come to sales people tell you these
Amazing efficiencies just got to bear in mind that is that actually seasonal is that looking at the entire heating season um but the good news is that heat pumps uh still work really efficiently in the winter and still give you a good efficiency that gives you good you know
Comparatively good running cost compared to gas boilers so it is an alternative that we can can consider even with um this so um how much space do we need for heat pumps so on the inside um compared to a Combi boiler it definitely needs a
Lot more space so this is a bit of a another limitation buildings that have got lots of Combi boilers might not be able to have heat pumps because they might not have the space in the way that they’re laid out for a retro for an existing property obviously if it’s a
New property you can do whatever you want with it um but with a heat pump we need to have a tank we need to have a hot water tank because unlike a gas boiler the heat pump cannot bring water from cold all the way up to shower temperature in
One Fell Swoop it needs multiple goes it needs to keep uh running and gradually bringing it up and that’s why we need to have the hot water tank and then as well as the hot water tank there’s a few other things as well technical things like the buffer tank so
The buffer tank is all about giving us enough volume for something called defrost so in the winter when it’s really cold outside and when it’s wet as well we start to get Frost over the back of the heat pump so you can see there’s a picture there with snowy heat pump in
The snow on the back of the heat pump you’ve got these fins they can literally get completely iced over a bit like in your freezer when you’re leave it for a long time try to get all the frost out you can have like a coating of frost in
The freezer you get exactly that coating of frost at the back of the heat pump so what it does is it’s quite clever when it sees it’s not getting enough air flow it switches um Direction and it takes heat from the house and quickly um evaporates off all
Of the Steam and you get a big Walling of steam coming off the heat pump like that and it’s completely clear again and it can carry on working but in order to do that it needs somewhere to take that heat from now we don’t want to make the
House cold because the whole point is to heat the house we don’t want to make the the water cold for showering because the whole point is to give us hot water for showering so we have our own dedicated minimum volume that we can always take
Some heat from that we can make that a little bit cooler to give us this capability to do the defrost that’s like the technical reason for these buffer vessels so because of these extra vessels that means we do need a bit more space we need a bigger kind of cupboard
We need basically a reasonable cupboard size for some of this equipment and some other Tech teal things here um sometimes you might want to do this as well which is basically um this is quite technical but it’s it maybe a bit interesting heat pumps have to always be able to work at relatively
High flow rates with a pump the pump similar to gas boilers some of them but even more the case it needs to be able to get water to flow through the heat pump because what you’ve got is a compressor that basically doesn’t really want to change too much once the
Compressor is working it doesn’t want to overheat if the heat pump’s over overheat it’s not good for them so we need to have a steady flow of water all the way through them to be able to work smoothly and sometimes when you’ve got modern systems like radiators we have trvs
Everywhere it’s building regulations to have trvs temperature uh regulating valves which basically will close the radiator when the room is warm enough so we don’t overheat rooms we don’t want to overheat unnecessarily overheat a room we want to be able to set it as hot as
We want and then stop using energy to that room when it’s enough and that’s what the trvs can do with the radiator system but the problem is if all the TRV is close then there’s less water going through the system same for underfloor heating if you got lots of rooms and
It’s a Well insulated house and they’re all warm enough they all switch off and then only be maybe one little room that’s somewhere at the top of the house that’s got very little insulation or something like that that keeps running and that will need some flow rate still
But not very much a small amount of flow so if we just let the heat pump only go through those Loops it would not have enough flow rate so one way to do is this low loss header where you basically allow um separate pumps to pump through
This buffer vessel and it means that one can work at a high speed and one can work at a low speed and they don’t have any problems between each other so again it’s technical but it’s interesting with a heat pump setup how much space do we
Need for a heat pump so that’s a little example of a a single fan heat pump um with with some of the space we need around the heat pump so important thing for us to Bear Mone in London is planning permission okay and there’s some really key quirky things about the
Plan permission that is quite is quite important to know if you’re going to do anything with heat pumps so one of them is one meter so to be permitted development to be allowed to put a heat pump in without going to planning it has to be a meter
Away from the boundary to your neighbor and that’s an old planning thing that comes from fire spread between buildings if there’s a fire in one building you don’t want to be a fire in another adjacent building so you don’t want anything that might catch fire a heat
Pump can definitely catch fire if there is a fire it’s got flammable gas inside so that’s if it’s within a meter then it needs plan permission the sad reality is that in London the size of all the buildings in London the best place to put it is normally always within a meter
Of the boundary because you don’t want to go if You’ got a small garden you don’t want to put the heat pump right in the middle of the garden you want to put it on the edge logically same in the front garden so sadly in many cases it
Makes most sense practical sense to actually put it in the boundary and apply for planning another one of these planning conditions is uh the volume of the heat pump so 0.6 M cubed is the threshold uh which smaller than that is permitted elements and bigger needs planning permission and what you can see
Here is a single fan it’s a heat with just one fan one fan blowing air if you got a double unit that’s got two fans that goes above that threshold that needs planning permission so any big heat pumps always need planning uh you to apply for planning the other um
Limitation as well is um what was the other one I was going to say um Cooling and the number of heat pumps you’re only put allowed to put one heat pump under permitted development so if you got two if you got one and an air conditioning unit then technically that needs
Planning anything that’s going to do cooling needs planning so if you go to planning what’s the danger so you got to pay a bit of money you got to do some drawings to show where the heat pump’s going to go that’s relatively easy um will they allow you or not generally if
It’s in the back Garden they never mind because basically the back Garden is your private space generally people can’t see into it so they don’t really care what’s going on there um with a Conservation Area the specific rule is it can’t be visible
From a road so if you can see it from a road then it’s more unlikely whether it’s going to pass the planning but with the heat pumps also what we can do is we can put them in an enclosure so we can put Timber around them in like a
Louvered profile that lets the air blow through but you can’t see through so often in front Gardens people have a big in store they might have a bike shed that’s maybe Timber and then you might also put a heat pump and no one really know which is which so they can in some
Cases as well be fine in a front garden but um there’s the location the other thing also is about noise so air conditioning systems were really noisy because they were just very cheap very cheap and cheerful and they didn’t get looked after much because you only use
Them for a couple of months in the summer and they quickly were working at like their worst possible operating capacity because if you don’t look after a system and you just make it work you know until it breaks then it’s probably going to be working not in its ideal
Scenario so a lot of air conditioning systems people were putting in were not they first weren’t designed to be quiet and then they weren’t being looked after so they were being really noisy and hence the planning brought in this whole rules about any kind of thing that’s
Going to make noise so the rules about noise for planning are quite strict it’s got to be very quiet the good thing is with the heat pumps is because they’re running through the entire heating season all the way through the winter they need to be night quiet because
They’re going to be a nuisance otherwise so a lot of the manufacturers have introduced a heavier units that are heavier so there’s less vibration U bigger fans that work at a lower speed so if you have a small fan that’s blown really fast it’s going to
Be noiser than a big fan that’s slower and um other kind of they also most of the heat pumps have um frequency controlled compressor so they can actually uh make the compressor run at a a slower speed when they need less power so it’s not always running at a fix
Speed it can actually slow down that also helps to keep it quiet and um the result of that is that most theat pumps are actually very very quiet the kind of good ones um however if you go to planning you may still be told to put an acoustic enclosure around
The heat pump so um that is kind of another thing to think about you know if you’re looking at the heat pumps those are the different different things um with the the planning uh and this is the uh the MCS process so if you are within that
Permited development you can um you can look at the distance to the nearest habitable room the nearest neighbor’s house and and that will determine if it’s going to bother the neighbors or not if it’s going to be a nuisance to them and all the different factors come
Into play so um I’ve gone on quite a bit today about heat pumps um there’s some nice things they got energy monitoring all the systems I install I try to give people energy monitoring so that you can see how much electricity you’re using if you switch from gas to electricity
You’re going to be using a lot of electricity you want to be able to look at that and check that it’s reasonable and then you know you’re not paying too much so it’s good to have monitoring where you can look at the data look the different months and the
Consumption um we won’t talk about any of those things um Dave did you get any pictures for the solar I was going to talk a little bit about solar wasn’t I um so we also do I also do I’ve worked in solar as well a lot solar panels and
Solar panels are a great thing as well to do in uh in London because London is very dry in the UK compared to the the West Coast so uh Bristol Manchester will get a lot more rain than we do in London London Norfork Hull all this East area
Is a lot drier so we get a lot of sunshine and um the price of solar panels has come down a lot over the last five years particularly when the uh war in Russia and Ukraine started the electricity prices went up that’s improved the payback for solar so the saving is much
Greater now as well with solar panels you’re going to save more money if you put them in and they um yeah so when the Ukraine war started the UK literally ran out of solar panels all of the big manufacturers got to the point where they didn’t have any solar panels in
Stock anywhere you could not buy a solar panel that’s how high the demand surged um last year and um it’s now started to kind of go back to normal again um but that was pretty extreme the growth of the solar PV um uh work at that time so
Um it’s uh there’s different systems I’ve got some pictures here this is on a flat roof so you’ve got a mounting system you don’t want it to be too angled on a flat roof because the wind loads are very high you need a lot of
Weight to hold it down we tend not to want to screw into a flat roof because that’s a penetration and that’s a point of leakage in the future but there are some systems you can get nickel some mounts is one system where you can have an integrated very clever waterproof
Seal so sometimes if a building is very tall and it’s very windy then you might want to pay bit of extra to make sure it really is fixed so it doesn’t have any chance of blowing off um but the low angle is to again reduce those wind
Forces um we’ve got another picture of oh what is that an in Roof System this is very popular if you’re redoing your roof if you got very old roof you’re going to take all the tires off redo the membrane and put new things on then you can have it integrated inof system and
There are some more pictures of that here as well so you can see it looks very flush with a tiles looks very nice I think it looks great and the other good thing is the birds can’t go underneath it so Birds specifically pigeons are the biggest issue with solar
Panels um of all basically and the reason is that when people go into solar panels like 10 years ago there was a big boom in the work that was being done and people didn’t really know about what they were doing there wasn’t that kind of time period of work going on to get
That level of kind of tried and tested and the pigeons love nesting under the panels so we can go to a on Roof System here that the small little Gap 100 Mil under the panel is the perfect pigeon nesting point because it’s dry it’s warm
From the roof and they can get in and out they can Nest but it’s the worst thing for your house because it can block up the drains it can create leaks it can cause a fire if the Hess is very dry and you’ve got uh short circuit for
A not very good connector that can cause fire um if a solar panel catches on fire it can be very significant it can actually burn the entire roof the entire everything can burn very significantly so what what you need to do if you are
In a house and there is a fire on the roof is to isolate the power they always have a red isolator and you is once the power is cut off to a solar panel there’s no fuel because the electricity will fuel the fire once it starts burning the electricity from the grid
Will fuel it to keep going so the moment you cut that power off it doesn’t have that fuel anymore and it can obviously keep burning what’s flammable but it won’t have that same Source question yeah yeah very good question so you repeat the question I repeat the
Question so so what she asked was about um the ask about the manufactur process of solar panels and also heat pumps as well saying that they use a lot of unsustainable materials rare earth materials and what is the we talk about the embodied energy and the the energy
And the manufacturer of these these good these Technologies how does that relate into the savings and the carbon emissions of the technology and um in the case of the solar panels they’re basically very very similar to TV screens they’re almost the same as an LCD TV just in reverse a TV
Generates light at certain particular wavelengths that we want and the solar panel absorbs light again at exact wavelengths that we where we want and so the same as with TVs or solar panels we can we can make them in such good um scales of economy so you can make so
Many in such a streamline way and the efficiencies that come with that is that even the the manufacturing process is very destructive does create a lot of emissions particularly with the resources um when you calculate when you divide up the number of panels you get out of it and they’re saving from each
One relatively actually it’s quite a low embodied cost it only takes about two or three years of use to save back the energy that was using its manufacturer because of this thing of scale of scale of economy um for the heat pump you’ve also got this interesting thing as well about
Heat pumps because they also use refrigerant gas and refrigerant gas is actually one of the main um pollutants in the world in terms of causing global warming because these gases that we talked about earlier so good at um boiling and changing State at low temperature they also trap heat
Very very well so some of the synthetic one synthetic ones are 600 2,000 times more trapping of heat than carbon dioxide so when the the heat pump breaks down and when has a leak and the refrigerant escapes into the atmosphere it’s actually doing Dam damage to global warming so in tropical countries where
There’s more air conditioning it’s less regulated you get a lot more of this uh release maybe you might think of in your cars Vehicles you have air conditioning in the car typically if you go to the mechanic and you say it’s not working that’s oh yeah the refrigerant is is
Level too low I’ll just top it up the mechanic tops up the refrigerant level and it just keeps on leaking and you use it for a couple of weeks over the summer and then the next year you come back and top up again and every time you’re doing that you’re releasing these Harmon
Refrigerants in the case of cars now because cars quite small air condition they’re able to use less damaging refrigerants fridges now use as well much less damaging FR refrigerants but heat pumps are still quite a big level of heat transfer they still need some of these refrigerants so um there were some
Moods for manufacturers to move over to What’s called the natural refrigerants which is propane is a natural gas that has a much less damaging uh effect on global warming in and um they’re a little bit limited though as well with how big they can be how close they can
Be to to buildings they got some other limitations um but again similar to with the solar if you look at the heat pump and the the refrigerant kind of downsides in comparison to the lifetime saving it’s a small it’s maybe 5% you know of the total embodied emissions of
That system um so it’s still you know still the right thing to do to be doing heat pumps even though they have these issues with them um particularly if the heat pump is um we looked at some of these systems like what we call a monol blocks so it’s got all the refrigerant
Inside the heat pump just go back oh it’s a different one it’s okay no it’s okay we’re still on these photos it’s fine so um yeah some of the heat pumps they don’t have very much refrigerant in them so even if it does escape it’s only 2 kilograms or less so
Not such a not such a big issue think time wise time wise we’re up to it might be good to um just have an opportunity for questions and we’ve uh maybe just a few questions before we move on to to uh some refreshments um there is a roving
Mic so uh if you could wait I’ve got the roving mic um so I will uh if if you just wait until you’ve got it and then ask the question yeah hi Casper do you have experience where with solar tiles yeah solar tiles good solar tiles is is basically taking a tile and
Putting a thin film solar panel on the tile it’s become now to a level where it is available commercially available you can buy it for domestic Market there are people who can do it the cost of the tile is about 2.5 times more for what you’re going to get out of it compared
To a normal solar panel so the economics of it are still a lot more expensive for a typical house like that cost maybe £6,000 to do normal solar panels you might pay double the price to do it with solar tiles so it does obviously take down the you know the payback uh but
It’s definitely something there are companies who can do it you know it’s definitely something that’s now available and reliable um I’ve done a few projects like that so um but yeah it’s much more expensive hi um if you were going to retrofit from a gas border to sour e
Pump would you need to completely repump or can you use the existing 15 mil pip work that goes around the house if you’ve got 15 mm pipe work everywhere in the house for anything other than a tiny building it’s unlikely to even be good with a gas boiler because a 50 mil pipe
Can only really heat up three or four radiators and it won’t have enough flow to do more than that and basically when radiators were first going in people working very hard high temperatures but when you’ve got a condensing boiler that is more efficient they only do condensing at heat pump temperatures at
Low temperatures so if you run a gas boil that’s condensing and efficient at a high temperature there’s no benefit with efficiency it’s like having an ancient boiler in terms of the efficiency you’re getting out of it it needs to run at a low temperature so for low temperature you need to have bigger
Radiators and bigger pipe work for better flow rates so generally if you’ve got a relatively new house with with a new gas boiler new radiators then it may well be fine if you got 22 mm pipes and if there’s you know ways you can sometimes you have pipes in different
Places um then it could be okay how would you make the Judgment between choosing to use solar PV as opposed to solar thermal given you’ve only got a limited amount of roof space and and money good question so I started doing solar THM work I’ve done a lot of
It myself I know a lot about it and very sad to stop doing it basically but the reality is that solar thermal gives you a saving on hot water only we can’t use solar thermal with space heating because the solar and the heating just doesn’t overlap well enough so it’s only for hot
Water so the saving from solar thermal is 30 50 80 pounds at the best and the cost of the solar thermal system is 4 5,000 time uh four 4,5 000 so there’s really no payback with a solar thermal there used to be Government funding there used to be 22,000 renewable heat
Incentive Jeremy was very lucky to have this green homes grant that gave even more funding for solar thermal for just a very short window but without that now there’s no funding now the payback is just not really there at all there’s no real Financial case for it with the
Solar PV panels is doing both it’s doing electricity and that electricity is so versatile you can use it for he with a heat pump you can use it for hot water so there’s much better ways you can make use of that electricity and even if you
Don’t use it uh octopus are paying 15 P per kilowatt hour for what you export so you actually can make lots of money of just exporting it so solar PV now the economics of it particularly with the higher gas electricity prices um are just very favorable so I tend I’ve yeah
Basically stopped recommending the solar thermal because of the lack of really Financial benefit from it um doesn’t mean it’s not a great technology amazing efficiencies because with a solar thermal system you’ve got heat shining on the panel you’ve got a tiny pump that works a fraction of the power that of
Energy you’re getting you’re looking at 400% um 4,000% efficiency with solar thermal because you’re getting just loads of free energy but the difficulty is that because it’s a plumbed pipe workk system and needs quite a lot of expensive components and the saving is sadly quite small
Uh thank you so much I’ve got a question um my wife and I live in a house from 1906 uh brick house and um trans uh transforming it for uh heat bump uh to make it effective for heat bump is out of the question unless we do major major
Work um how about just a top up heat pump for one room where we sit most of the time one large room kitchen dining and no tank and minimum of piping just simple top up heat pump so it’s a very good question so the question is basically uh limited fabric improvements
Is a heat pump still viable and then you’re also asking about if we’re doing zoning so we’re not heating the entire house zoning is very clever for uninsulated building because if the building is not well insulated the question then is do you need to heat
Every room you know or can you just heat the rooms that you’re using most and um the sad thing though is that any system that doesn’t if the heat pump doesn’t replace the entire existing system you won’t get that government subsidy which is significant £7,500 is significant so
That’s the main kind of drawback from only doing a partial Improvement and the reason why they’re not allow not paying any partial improvements is because in the past lots of people put heat pumps in as a hybrid system and the heat pump ended up not doing anything because of
The way that they balanced the two systems the gas boil ended up just doing all the work and so it’s very hard for them to check that of way the way it’s actually it’s configured and so they decided just to not subsidize us even though they can be very good um but yeah
In in that situation putting a heat pum there does just certain rooms when it comes to the cost of improving a room as well if you look at room by room and improving rooms it can be a lot cheaper rather than you know improving the whole room and often you’ll find that
Insulating ceilings and stuff can actually make rooms can be very energy efficient even though the house is not energy efficient rooms can also be very airtight as well you can have very little ventilation coming in lots of problems of condensation because we haven’t got enough fresh air coming into
Rooms that are very airtight even though your stairwell can be very leak key you can have loads of air leakage in a stairwell then you go into the room and the room’s like completely airtight so it is important to look in a house at locally what’s going on so for one woman
A tank W won’t be necessary so if you’re looking at um doing a system that isn’t doing hot water then you’ll have to have some other system for hot water but it’s perfectly there’s lots of options there’s loads of options what you can do okay I think um there are three more
Questions but what what I would suggest uh maybe is that we move into those questions um because caspas very kindly agreed to stay and have a cup of tea with us um and so what we could do is we could bring this part to a close and
Those three people uh I’m sure Casper would be happy to to be approach approached um to to ask those questions so I would like to um say thank you on behalf of all of us for for Casper for for coming out this evening and for a really fantastic talk thank you very
Much and uh I would like to to put in a plug uh two plugs next week um an energy saving Mary’s holding it up energy saving evening where um there are it’s going to be interactive it’s going to be team based it you’re going to learn a lot but
It’s going to be fun as well and there there’s chocolate involved um and the and it’s here next week uh that’s the last talk the other thing is to encourage all of you if you’re not already members of uh muswell Hills sustainability group it is fantastic value £10 a year for an
Individual1 a year for two people at the same address um I would very strongly warmly encourage you to um sign up uh do not delay and now we have um some refreshments so if you want to hang around for a bit and if you have those questions um
Then uh you’re very welcome to do so thank you very much for coming I we have recs thank you