วีดีโอ

@winstonfox4457 What a strange comment. You sound sad and bitter. I would advise that seek help for your anger issues. Best wishes Michael

Lots to comment on here! “Hi. Thanks for the info. Amazing! My house is 306m². 9" solid brick. New roof (fully insulated) and windows in 2013. I'm in the process of insulating the ground floor crawl space. 116m² Using my average of 32,000kwh of gas and a 80% efficiency for the boiler and using my heating degree day. A heat pump size of 10kw is being suggested ! Amazing. I heat the house to 19.5c 2 hours in the morning and 7 hours in the evening. I also use a 8kw stove on the colder days.” The Rule of Thumb should work if during the heating season your home stays at roughly the same temperature during the day and night. “I'll get a heat geek heat loss survey done in the new year. £500 though. Ouch! They'll monitor the house over a few days.” Good idea. It’s real money, but it’s real work and expertise and genuinely valuable insights. “A local ASHP installer estimating an heat loss of 20 kW! It was an educated guess. Am I right in thinking a 22kw system (Two 11kw HP Mitsubishi Cascade system) could produce 528 kWh of heat per day? “ Yes “Looking back at my Octopus data (only from March 2023) my highest gas heat load was 165 kWh (at 19.5 °C).” 165 kWh/day is equivalent to just under 7 kW. Near to me in west London the average temperature in March 2023 was 8.5 °C and teh coldest temperature was - 2°C on teh 11th March 2023. I would guess your peak demand would not be much more than that www.wunderground.com/dashboard/pws/ITEDDING4/graph/2023-03-8/2023-03-8/monthly Do you have data from January - there were some very cold days this January 2024 (16th to 19th in the London Region). This would give you a very good idea about your real heat demand. 10 kW corresponds to 240 kWh/day “To be honest, the house could be a little warmer sometimes. It's finding the balance between cost and comfort. Fingers crossed, both will improve with an ASHP.” Each extra degree Celsius increases heat load by around 12%. I have 9.24kWp 15 panels south 7 west 6kw Solaredge Homehub inverter 10kw Solaredge battery. 100amp. Single phase. System predicted to produce 8.4Mwh per year. I've exported 2MWh this year. I wonder how much of the heating demand will be covered by solar? Not much of your heating demand will be covered by solar because obviously the solar peaks in summer and heating peaks in winter. But it should not be zero. On my system - smaller than yours - in December and January I get ~ 3 kWh/day, which corresponds to about 10 kWh of heating. It gets better in November and February and is quite substantial - maybe 50%? In March and October. "Thanks again. " You’re welcome. Good luck with your endeavours

Thank you for your kind words. Regarding your particular questions. First of all, please remember that this is a rule of thumb. In calorific terms 2,000 litres of fuel oil consumption is roughly equivalent to around 20,000 kWh of gas. So if this is your annual usage, then this would suggest very roughly 20,000/2,900=6.9 ~7 kW maximum heating demand. This assumes that (a) the dwelling is kept at a roughly uniform temperature throughout the heating season and (b) you hot water usage is not crazy. If you switch heating off all day nd then blast it on for a couple of hours in the evening then this may cause the formula to underestimate your heating requirement. If you do use a lot of hot water then the formula will overestimate your heating demand. However you are right that many oil burners are not as efficient as modern gas boilers. The 2,900 number in the formula assumes 90% efficient burning so if the oil boiler is only 75% efficient, then the heat load will be less. 20,000 kWh of gas burned at 90% efficiency yields approximately 18,000 kWh of heating in your home. 2,000 litres of oil is equivalent to 20,000 kWh of gas burned but only at (say) 75% efficiency and so yields approximately 15,000 kWh of heating in your home. So the estimate of a 7 kW heat pump would be an overestimate. A better estimate would be around 75%/90%= 0.833 * 6.9 = 5.7 kW. In practice a 7 kW might well be a good fit giving you some headroom and faster re-heating of domestic hot water. The 'comfort' issue is difficult to assess qualitatively. In my house, all the rooms are at a very similar temperature all the time. This is a pleasant environment to be in. Now at the moment - and through previous winters - our internal temperature is a smidgeon over 21 °C which is hotter than teh 20 °C set point, but we have not tweaked teh system because we just enjoy it! Every extra degree Celsius causes around 12% extra heating demand. Best wishes in your endeavours. Michael

@@michaeldepodesta001 Thank you for such a comprehensive reply. We are probably not typical in that we tend to keep our house cooler than most but use a multi fuel stove in the living room for local heat. Using two digital thermostats one upstairs and one downstairs we have downstairs at 18C in the morning for 2 hours and 6 hours in the evening. We also have upstairs at 18C in the morning for 2 hours but only 3 hours in the evening. In between these times the temp is set to 14 or 15C so basically off as the temps rarely fall so low unless it is very cold outside. I understand with a heat pump I would need to have more even temps throughout the day, that would be OK as it would give more comfort but I guess might confuse the calculations. Hot water wise we probably use a tank of water most days which I believe will be around 5 or 6kWh based on what our solar Iboost uses to heat the tank. So from these calculations we could estimate a 7kW HP would be sufficient but if I decided I would quite like the house a bit warmer then maybe a 9kW HP would be a safer bet. We might also be able to retire our multi fuel stove. Or are we better to keep to the 7kW HP and use the stove on the coldest days? I hear conflicting advice on whether over sizing a HP is a problem. Obviously I need to get any installer to do their own calculations but at least I now have a useful estimate and if they say we need 15kW HP I can tell them they need to redo their calculations. Thanks again for all your help.

Dear typxxilps, Good Evening. The key is the title: this is a "Rule of Thumb" which translates in german as "Faustregel". This is not the same as heat loss assessment for a home. The idea was to allow people to easily estimate the likely heat pump size. Many people fear they will need huge heat pumps and in the UK it is commonplace for heat pumps to installed at twice or three times the optimum size. Indeed, gas consumption will vary from year to year, but the rule incorporates some leeway for that. Ideally a heat pump should probably have a little headroom, but if not then it is not a disaster if the house gets a little colder for two or three days a year. You might find this article interesting. protonsforbreakfast.wordpress.com/2024/10/08/deliberately-under-sized-heat-pumps/ Best wishes Michael

Good Morning. If I understand correctly, in a condensing boiler then the water vapour in the combustion exhaust is condensed by having the inlet cold water pipe flow around the exhaust. This condenses the water vapour, releases extra heat and the condensation is captured and dripped away outside. In a non-condensing boiler, the hot exhaust gas flow straight out of the house. So I don't think lowering the flow temperature could cause condensation. Lowering the flow temperature bit by bit is a smart way to (a) reduce bills now and (b) see if your system is heat pump ready. Obviously the best test is on a cold day. The article below summarises my heat pump performance over the last three years. In my installation, the evidence shows that the low-loss header did not make a difference: it was unnecessary. But neither did it seem to do any harm! Plumbers explain this badly, but roughly speaking, if an installer does not know what the radiator pipework is like, then installing a low-loss header is like an insurance policy: It makes sure that the installation will work - but it may not be optimally efficient. protonsforbreakfast.wordpress.com/2024/08/21/2024-summer-summary/ I think low loss headers and buffers are different. I think a buffer adds some water volume to the system to prevent the heat pump cycling on and off too quickly. I think a low loss header is used to match the flow impedance of the radiator network to the hydraulic pumping power of the heat pump. Do get back to me if this isn't clear. And good luck with your endeavours! Do visit some owners (or me! I'm in Teddington) to see how they feel about it app.visitaheatpump.com Best wishes M

@@michaeldepodesta001 Thanks for your reply, and a very good video btw. Its widely said across the Internet that you should avoid flow temps below the dew temp in a non condensing boiler as it will allow condensation that will cause corrosion of the boiler (and I presume a water leak as there is no means to capture the condensate). I was challenging that to see if it mattered for a just couple of days or so. Otherwise I would have done it years ago 😉 I would do the test when its colder. I thought a volumizer adds water to the system (to aid defrost for example) but a buffer reduces cycling when the flow rate isn't high enough to exact the heat (e.g. with some microbore). This sounds like what you are describing as a low loss header, so maybe there are the same? Btw, love physics, especially "spooky action at a distance"! Life relies on it, e.g. neurons simultaneously firing 👍And nuclear fusion is still "only 20 years away" 😄

Good Morning. A gas consumption of 11,460 kWh is below average for the UK, but your detached 4-bed house is probably larger than average in the UK. And yes, 6 kW peak heating requirement would sound like a good first guess. This is just a rule of thumb, and it can give misleading indications for a couple of reasons. If the house is unheated for long periods of the day, e.g. when everyone is out at work, and the temperature falls then the gas consumption corresponds to a much lower average temperature - and every degree Celsius change in average temperature represents about 11% in gas consumption. Alternatively I note you have 4 adults. If they were in the house all day, then this corresponds to 400 W of heating i.e. 9.6 kW/day of heating, or 3,500 kWh of additional heating. Similarly, all electrical consumption ends up as heat, so if your electrical consumption were particularly high, this too could be heating the house. Without details I can't really help. You could try measuring gas consumption and electrical consumption on a very cold day and then work out the required heat pump size from that. Best wishes Michael

@ed4468 Thanks for your comment which is the most asinine of the 350 I received so far. Well done! "why cant he be down to earth and say if you buy a 3kw heat pump its good enough for an average home to heat radiators and run a shower, etc, ffs!, total bollox video." Because saying that would be untrue. Best wishes Michael

Indeed. As you say, it was for the purpose of being explicit.

@alansailing1387 Good afternoon, The method might possibly work. If your gas usage is mainly for winter heating then it should give an indicative value of heat pump size, but if you are using a lot of your gas on something else (a hot tub?) or if you use more than 5% of your gas on hot water heating, then the formula may be inaccurate. I downloaded the monthly HDDs for Melbourne Airport in Victoria. Taking them in 12 month groups, it seems the HDDs are around 1200 °C-days per year. The base temperature of 16.5 °C corresponds to keeping a home at roughly 20 °C. Typically, people don't put the heating on until the outside temperature falls about 3.5 °C below their desired internal temperature. Using the formula at 13m07s in the video the HTC for your dwelling appears to be 593 W/°C. i.e. it takes 593 watts to warm your home by 1 °C. In UK terms this is a very large dwelling or a very leaky dwelling. In terms of heat pump size, If the minimum temperature in Melbourne falls to around 0 °C then you would want a heat pump with a power of 20 x 593 watts which is about 12 kW. Does any of that make sense? Best wishes Michael Description: Celsius-based heating degree days with a base temperature of 16.5 C Source: www.degreedays.net Accuracy: Estimates were made to account for missing data: the "% Estimated" column shows how much each figure was affected (0% is best, 100% is worst) Station: Melbourne Airport Comparison, VIC, AU (144.91E,37.73S) Station ID: 95866 Month starting HDD 16.5 °C days/year 2021-07-01 206.5 1138.9 2021-08-01 163.3 1163.6 2021-09-01 130.8 1171.9 2021-10-01 110.7 1187.9 2021-11-01 79.6 1173.8 2021-12-01 36.7 1180.9 2022-01-01 1.7 1194.3 2022-02-01 10.9 1202.0 2022-03-01 15.2 1208.3 2022-04-01 49.8 1215.9 2022-05-01 140.1 1237.2 2022-06-01 193.6 1245.4 2022-07-01 231.2 1216.6 2022-08-01 171.6 1156.9 2022-09-01 146.8 1148.8 2022-10-01 96.6 1106.2 2022-11-01 86.7 1115.0 2022-12-01 50.1 1070.5 2023-01-01 9.4 1039.8 2023-02-01 17.2 1038.4 2023-03-01 22.8 1032.7 2023-04-01 71.1 1033.8 2023-05-01 148.3 1042.4 2023-06-01 164.8 1027.4 2023-07-01 171.5 1063.7

@frederickbowdler8169, Good Evening, Thank you for your kind words. Do drop me a line if you have any specific questions. Best wishes Michael

And a dust mask of good quality should be worn (mandatory)

@frederickbowdler8169, Good Evening. I think there is still a lot of poor practice amongst installers. But my experience is that even in the last two years, standards have risen substantially, and I think that's a trend that's likely to continue. I certainly hope so. BEst wishes Michael

@frederickbowdler8169 Good Evening, Reliability is an important issue, and it it is yet to be really tested in practice because heat pumps have not been installed long enough. But the technology is similar to that in domestic refrigerators and air conditioning units, both of which are spectacularly reliable. Was it something specific that caused you raise this concern? Best wishes Michael

@adzy166, Good Evening. Sadly I don't think I have enough information to be able to help you. Do you know how much coal you use in a typical year? If I knew that figure and your location I could probably make a guesstimate. "We’re currently going down the solar PV plus ASHP route". Can I suggest that you consider purchasing a battery as well? In summer the solar PV can charge the battery which can run your home overnight. In winter you can buy cheap rate electricity and then run the heat pump from that for some fraction of a day. The savings can be very large. Best wishes Michael

@Mentaculus42 Good Morning. Regarding CO2 sequestration. There are many options for removing CO2 from the atmosphere and I hope that by the required time we will be able to pull a few billion tonnes per year from the atmosphere. But there are no extant plants which can sequester 100% of CO2 captured from combustion. Roughly speaking, if a venture wants to keep burning something, then it's just a way for existing oil and gas to limp on. Regarding China: The entire solar revolution is powered by China. And the country is taking big steps in the right direction, but they are constrained by realpolitik. As is the United States which is *still* increasing oil production. It's easy to criticise other countries. Regarding cars: No. ICE cars are in terminal decline and BEVs are growing each year. And the technology is getting better and the cost is getting lower. Best wishes Michael

Then what is your solution to dealing with fugitive bio-methane that is and will be released directly into the atmosphere with a near term heating effect 100 times more than CO₂. In California this problem is recognized as something that has to be addressed and thus the economy incentives via LCFS (low carbon fuel standard) SUBSIDIES to collect and use this CARBON NEGATIVE (as scientifically certified) transportation fuel source! If you don’t collect and sequester the CO₂ (which converts it to an even more highly carbon negative energy source) then the methane emissions will be doing the worst possible thing. If the evil fossil energy industry were to disappear over night, the bio-methane fugitive emissions will still exist and will be left unabated. Admittedly I understand the mental connection between biofuels and fossil fuels but that erroneous connection doesn’t automatically make bio-methane a method to “greenwash” the old fossil fuel industry. In California it is almost totally a separate and new industry that is highly monitored by CARB. In addition, it is MANDATED to use BIO-METHANE in the existing transit CNG buses in California to provide an economic pathway to remove the bio-methane emissions from the atmosphere. So there is a problem, what is the solution? I have never understood why the “green group” is not willing to see climate change from the larger perspective. Also the world’s “old fossil fuel industry” is not going away, the “green group” solution is to WISH THEM INTO OBLIVION!! The problem is that is not going to solve the big picture climate problems. One has to have something more than WISHFUL THINKING to save the planet. So I challenge you to address these realities. Also, those numerous NEW CHINESE COAL FUELED POWER PLANTS (locally commissioned) destroy any HARD WON and COSTLY progress that California has achieved. The interesting thing is the climate catastrophe can only be prevented if the whole world is going in the correct direction and ALL PARTIES that have an impact are cooperative (otherwise we all burn).

Then what is your solution to dealing with fugitive bio-methane that is and will be released directly into the atmosphere with a near term heating effect 100 times more than CO₂. In California this problem is recognized as something that has to be addressed and thus the economy incentives via LCFS (low carbon fuel standard) SUBSIDIES to collect and use this CARBON NEGATIVE (as scientifically certified) transportation fuel source! If you don’t collect and sequester the CO₂ (which converts it to an even more highly carbon negative energy source) then the methane emissions will be doing the worst possible thing. If the evil fossil energy industry were to disappear over night, the bio-methane fugitive emissions will still exist and will be left unabated. Admittedly I understand the mental connection between biofuels and fossil fuels but that erroneous connection doesn’t automatically make bio-methane a method to “greenwash” the old fossil fuel industry. In California it is almost totally a separate and new industry that is highly monitored by CARB. In addition, it is MANDATED to use BIO-METHANE in the existing transit CNG buses in California to provide an economic pathway to remove the bio-methane emissions from the atmosphere. So there is a problem, what is the solution? I have never understood why the “green group” is not willing to see climate change from the larger perspective. Also the world’s “old fossil fuel industry” is not going away, the “green group” solution is to WISH THEM INTO OBLIVION!! The problem is that is not going to solve the big picture climate problems. One has to have something more than WISHFUL THINKING to save the planet. So I challenge you to address these realities. Also, those numerous NEW CHINESE COAL FUELED POWER PLANTS (locally commissioned) destroy any HARD WON and COSTLY progress that California has achieved. The interesting thing is the climate catastrophe can only be prevented if the whole world is going in the correct direction and ALL PARTIES that have an impact are cooperative (otherwise we all burn).

No. High combustion efficiency? If a small plant is better than 30% I woul die surprised. And if I need 10 kW in summer how would I get rid of the 6 kW of heat ? Negligible release of methane? 1%? My view is that if the solution involves burning stuff, then it is unlikely to be a solution. That technology may well have niche applications, but it doesn't look to be a suitable for scaling. Best wishes Michael

@@michaeldepodesta001 The Karno is 50% thermal to electric out efficient, not your 30%, so … The combustion efficiency is extremely good because it is a Sterling engine and hence is not an ICE. As far as I can tell, you are somewhere around London. So you have a rather higher heating requirement than cooling. I wouldn’t expect that you could think of using an “absorptive cooling system” but since you have an asymmetrical yearly energy requirement biased to the heating side, you don’t need to. I notice that you rigidly follow the “green” and not “clean” storyline. That type of thinking is what will cook this planet.

@@Mentaculus42 Good Evening, 50% efficiency is excellent. Yes, I live in West London and heating in winter is more important than cooling in summer. I'm afraid I don't know what you mean by "absorptive cooling system". I also don't know what you mean by "rigidly follow the “green” and not “clean” storyline" . My concern is the emission of greenhouse gases and this video I was talking about home as a whole. In the past the idea of using a home generator and using the heat for heating and the electricity for export seemed like a great idea. But the problem is the path to scalability. For heating a home, nothing beats a heat pump: nothing comes close to being 350% efficient. Heat pumps are getting better and cheaper. The Karno device requires a methane supply (which leaks) and which emits CO2. You are use that methane can be generated in a processes that absorbs CO2 from the air, but to provide that at scale will require immense use of land and suitable crops. And in the mean time, regular fossil gas will continue to be mined and burned. I have absolutely no agenda. I just want to stop us emitting CO2 (and methane) as fast as possible. Best wishes Michael

@@michaeldepodesta001 You do understand where bio-methane comes from? The most carbon negative bio-methane comes from dairy cows with the use of anaerobic digesters and then collecting methane generated within dumps. This methane will be released to the atmosphere if not collected. Since it is biologically produced, the original carbon was removed from the atmosphere by growing the feed for the cows. The carbon NEGATIVE aspect comes from the avoidance of releasing methane directly to the atmosphere which is much worse than the CO₂ being generated by combusting the carbon in the methane which came directly from the atmosphere in the first place. So in one way you can say it is carbon neutral but the certification of each methane source takes into account the methane avoidance which usually makes dairy methane carbon negative. If you combust and then sequester the CO₂ it makes it extremely carbon NEGATIVE. California has a huge dairy industry and this is a way to provide a solution to part of the methane emissions problem. Do remember that this methane has been historically released to the atmosphere. So in California the CNG transit buses are mandated to be fueled by RNG. After 2030 the transit agencies will be required to buy EV or hydrogen fueled buses. As it stands now, RNG can’t scale enough to replace all the diesel fuel used for trucking but what is produced is subsidized sufficiently to be cheaper than using diesel. Admittedly some of the pipelines that move fossil methane are used and that can be viewed as propping up the fossil industry which in this case is unavoidable. Generally the pipelines are owned by the utilities and not fossil methane producers. Now I do understand that the upstream leakage of bio-methane could be an issue as it is with the transportation pipeline and compressors needed for the fossil methane. But the fossil methane leakage associated with production is not there. To me this is a big win for the environment with little economic benefit going to the old oil companies. The issue that should and is of concern to the green groups is how the old fossil energy industry moves forward as they “reinvent themselves”. The green vs clean is very specific terminology that differentiates how hydrogen is produced. So you can have green or clean ammonia for agriculture which requires the production of hydrogen. Green hydrogen is produced from electrolyzed water and renewable energy. Clean hydrogen is not produced that way and is generally criticized with great intensity by the green advocates. But the world needs low carbon ammonia, low carbon steel, low carbon cement, low carbon ship fuel, low carbon aviation fuel, etc …

Dear @adblocker. I'm sorry but that's all too common. If not used by experienced people, the software which calculates the heatloss tends to overestimate heat loss quite badly. I wish I could say something to practically help, but the only thing I can think of is that the situation is improving slowly. I know it doesn't help you. Sorry. Best wishes Michael

@@michaeldepodesta001 hi thank you for replying. Money is not an issue for me (as long as I can get the boiler upgrade grant) I’m happy to get a heat pump installed. I’m also getting a 12kw PV array installed with Tesla Powerwall3. As soon as that is installed in the next couple of months I will get the heat pump. My concern is I want the house to be entirely self sufficient in regards to energy use. If the heat pump needs to be massive my solar panels may not be enough. Should I get another company to do the heat loss calculations? Any recommendations?

@@adblocker276 Good Evening. First of all congratulations! That sounds like a super system I am sure the combination of panels and a Powerwall 3 will give you splendid results. I don't think that you will be able to become self sufficient all year round. I don't know where you are, but in the UK for a south-facing system, a 12kW-peak array (which is MASSIVE! 36 panels!) will yield ~50 kWh/day on average in summer but it's winter yield will average 10 kWh/day *at best*. But winter generation depends strongly on shading low to the horizon. 10 kWh/day is enough to cover normal household usage, but if you are running a heat pump your winter usage will rise considerably. In my home it peaks at about 25 kWh/day. I would not worry about this: you system will keep you off grid for many months of the year (perhaps 6 months) and you will have very small bills in all but the coldest months. And you will export a lot of electricity. Regarding your heat pump, I would recommend you stabilise your house at a comfortable temperature, and take weekly measurements of gas consumption over the winter: this will tell you the actual amount of heating you use to keep your home as want it. If you use 700 kWh of gas in a week then with an 85% efficient boiler that will deliver ~595 kWh of heat which corresponds to about 595/7 = 85 kWh/day which is an average of 3.5 kW. You can also make the same measurements on a very cold day to work out the biggest daily usage. It may feel frustrating to wait but when you know for sure the size of heat pump you require, you will feel much more comfortable about the installation. Best wishes with your endeavours. Drop me a line if you would like advice about the measurements. Michael

@peterkis5442 Good Evening, In your comment you states that: "The HTC is inversely proportional to the base temperature". No! The Heat Transfer Coefficient describes the way heat flows into or out of the dwelling. It describes the way the dwelling loses heat. You calculate two examples of HTCs, HTC#1 and HTC#2: ***THESE DESCRIBE TWO DIFFERENT DWELLINGS*** In the first dwelling 25,000 kWh are used per year to maintain it at 10 °C: In the second dwelling 25,000 kWh are used per year to maintain it at 20 °C: Clearly, the second dwelling is much better insulated and so it needs a smaller heat pump. OK? Best wishes Michael

Thank you :-)

Richard, thank you for your kind words. Best wishes: Michael

Eddy, thank you for taking the time to drop me a line. It's always heartening to know the rule of thumb still works! Good luck with your endeavours: If you choose to go ahead with it, I hope the installation goes well. Best wishes Michael

@@michaeldepodesta001 Hi Michael, I'm waiting for the new Octopus Cosy to come out, unfortunately that will be a 6kW device so I might be waiting a while for a larger version to be released.

​@@eddyd8745 Yes: don't be in a hurry. This is a great time to start monitoring weekly gas and electricity usage - very little now so the gas consumption is just from cooking and hot water preparation. Maybe you will get a chance to measure over winter and see how the gas consumption goes. A 6 kW heat pump will produce 6 x 24 = 144 kWh/day of heat. You can check whether that's enough for you. Best wishes Michael

In the video (th-cam.com/video/n3AoUjuBixA/w-d-xo.html) I explain the typical saving is small and I also say exactly how much my bill is. If you want to comment on the video, you might want to watch it first. Best wishes Michael

Robin, Thank you for your kind words. The Milankovitch cycles operate very subtly. This page from NASA has an excellent graphic explaining the three main cycles. science.nasa.gov/science-research/earth-science/why-milankovitch-orbital-cycles-cant-explain-earths-current-warming/ For example our seasons are determined by the angle of the Earth's tilt towards the Sun. Northern Hemisphere summer is when the northern hemisphere points towards the Sun. But our orbit is not quite circular: one axis is 1.7% longer than the other axis. Currently Northern hemisphere summer occurs when the Earth is farthest away from the Sun. Over time this will shift and Northern hemisphere summer will occur when the Earth is closest to the Sun, adding a little more summer sunshine. These changes affect the amount of sunlight reaching Earth by just a tiny amount. But the critical region is at higher latitudes of the northern hemisphere. Here the changes have the effect of lengthening or shortening the summer, and what happens at the snowline is critical. The snowline is the nominal latitude which remains snow-covered over the winter. A systematic cooling in this region allows the snowline to advance south, increase the reflectivity of the Earth and reducing organic activity. The snow covering is unstable against this kind of change, and if it occurs year after year for thousands of years, the snow-line can advance toward the Equator. These tiny effects - globally just a change in solar input at the percent level - can push Earth into an Ice age. Similarly, such changes can push Earth out of an ice age. To me this just confirms the extreme sensitivity of the Climate to small perturbations. And the current perturbation - with CO2 rather than orbital changes - is large on this scale and it's more rapid than anything in history. It's still not clear whether we have created enough heating to melt the Greenland Ice Sheet (7 m of global sea rise) or the Antarctic Ice Sheet (21 m of global sea rise). Michael Mann discusses this in his book Our Fragile Moment (www.amazon.co.uk/Our-Fragile-Moment-lessons-survive/dp/1915590515). In the last interglacial period (which was warmer than now) the evidence is that the ice sheets did not melt then, so maybe we are safe from that. But there are other factors at play too - the rapidity of the rise and the role of pollution. As I said - so much to discuss! Best wishes Michael

​@@michaeldepodesta001 Thank you Michael. It seems that the pace and magnitude of the other factors are negligible compared to the contribution of carbon dioxide over a time period of hundreds of years. Indeed the Nasa article points out that based on the Milankovitch cycles alone, we are currently in period where the earth should be slowly cooling. Thank you for all the extra information, - very interesting but worrying at the same time. Education is the key and I applaud your efforts cut through the noise and share you insights through these informative videos and your blog.

Jean, yes. Warming at 0.2 °C per decade gives us very little time to respond. Best wishes Michael

Mmm. Yes, I was a lecturer in Physics for a bit under 20 years, at Birkbeck College and University College London. There I literally wrote a text book on the properties of materials, which is very useful if you want to understand the phase changes in either boilers or heat pumps. Then I moved to the National Physical Laboratory where I worked for 20 years as an expert in temperature measurement. At NPL I made the most accurate temperature measurements ever made and carried out work leading to the re-definition of what we mean by "one degree Celsius". I was also honoured to be awarded an MBE for my services to science. After retirement I used all my skills to monitor my home and publish the results so that others could learn from both my mistakes and successes. From your comment: "Knowledge, du! :College Lecturer for over 25years!" you seem to show contempt for people who actually know things. This ties in with your previous comments which seem to be along the lines of "I know a bloke who said...". Perhaps if you spent a few years at University you too might learn a thing or two. Best wishes Michael

Thanks for your kind words. M

I have not said "Everyone should have a heat pump". If you want heat pump, they can work in any home heated by a gas boiler. If you don't want a heat pump: don't have one. But if that's your choice to keep using a boiler you will never benefit from the splendid cheapness of heat pump operation. Best wishes Michael

@kevinw7419 Good Morning. I am puzzled as to how you can have such strident views and be so completely WRONG! In my house, the heat pump did just replace the boiler and we did not change our radiators. That's not the case in all homes but it is in many homes. Flow temperatures are typically in the mid 30's and reach 45 °C when it is -5 °C outside. These are just facts: i.e. Physical Reality. My home has solar panels and battery storage and a heat pump. Last winter teh average internal temperature of my home was a cosy 20.5 °C pretty much 24/7. Last year my annual bill for heating and all electrical use was £450 and this year (because of a better tariff) it will be around £250. In short you are talking nonsense. Like I said, I am puzzled as to how you can be so opinionated and yet so completely wrong. Curious. And aside from being cheap, it emits dramatically less carbon dioxide. Best wishes Michael

You may have a point on Some properties highly insulated, but the majority it will cost too much and the flow temperatures in a lot of properties won't be good enough, fact!! A suitable electrical boiler with solar and batteries has to be a great option with the battery back up I would be looking for zero electrical bill, not £250!! Why aren't all gas engineers jumping on board with the heat pump idea? Well they just aren't good enough Yet for everyone, fact!

@@kevinw7419 Like I said previously, I am puzzled as to how you can have such strident views. You don't seem to have any special knowledge or experience. You are just spouting opinions. In contrast my 5 years of measurements on my home and my 20 years of experience as a metrologist show me the reality. You are welcome to ignore it. And good luck with your attempt at a zero electricity bill using resistive heaters! When you have achieved that I will look forward to watching your TH-cam video on the subject. Best wishes Michael

Dear @nattyco, good evening, Did you mean 10 kilowatt *hours* per day? That doesn't seem a lot to me: most houses require closer to 100 kWh/day. But you haven't given me enough data to really make a judgement. In any case, I wish you all the best in your endeavours. M

Good Morning. This is also true in the UK. If I remember correctly (please check) 1 cubic metre is about 11.4 kWh of energy. The number varies through the year due to small changes in the composition of the gas. In the article below I explain how to raise energy consciousness by converting meter readings to energy readings in units of kWh. protonsforbreakfast.wordpress.com/2022/11/14/energy-consciousness-raising/ Best wishes Michael

Keith: Thanks for your kind words: and good luck with your project. It's all still much harder than it should be! M

@PaulRansonArt, thanks for stopping by. Three points in response to your comments. Firstly, with regard to embodied carbon dioxide in the panels and heat pump, that 'debt' is paid back in a year or two. Here are my calculations from a year or two ago. protonsforbreakfast.files.wordpress.com/2022/01/image_2022-01-01_172251.png The figure is part of this article protonsforbreakfast.wordpress.com/2022/01/02/carbon-accounts-2021-looking-back-and-looking-ahead/ Secondly, financially a heat pump by itself is borderline 'profitable' i.e. it has a long 'payback' time. However in terms of reduction in carbon dioxide emissions the payback effect is dramatic - resulting in ~80% emissions reductions. In terms of capital outlay, for many homes the UK government's £7,500 grant makes a heat pump installation similar in cost to replacing a gas boiler. Finally. Metaphorically we have set our house on fire. Putting out the fire does not come at zero cost. Best wishes Michael

@@michaeldepodesta001 I absolutly agree with your comments. We as a planet have no option other than to adopt a greener way of living. Such a shame that energy companies saw the £2,500 additionally grant as a windfall for them. Yes, my quote for a heatpump was £3,659 in addition to the £5,000 grant. When I saw the additional boost to the grant I leapt for joy as my quote would be reduced to £1,159! Right ....... think again. The quote remained unchanged but they would have pocketed the extra money. How on earth is this going to encourage us to change. My total investment on a solar system, batteries, and an ASHP would be £17,000. Add an EV and we're up to £50,000. Keep on making great videos and lets pray the economy of scale makes a greener solution affordable for everyone.

@@PaulRansonArt Oh Dear: that sounds depressing and potentially rage-inducing! I wish it were not so. Please allow me to wish you good luck with your endeavours. Michael

Dear @dellybeanhead, Good Afternoon. Running a heat pump with a battery is very smart. With Octopus;s different tariffs it is very hard to know which one is optimal, but I use Octopus Intelligent Go. The terms have got better than Octopus Go. Intelligent go: 7.5 p/kWh from 11:30 until 5:30 i.e. 6 hours Go: 7.5 p/kWh from 00:30 until 4:30 i.e. 4 hours. I use this with a Tesla Powerwall 2 (13.5 kWh with 5 kW of power). My house has a *peak* heating demand around 70 kWh which requires round 20 kWh of electricity to operate the heat pump. More normally the house requires ~ 20 kWh of heat which requires just 5 kWh of electricity. So in winter we charge the battery (and run the dishwasher etc) in teh cheap hours and then run off the battery until it runs out. On teh very coldest days his happens at around 1:00 p.m. and we have to run on full price electricity. But normally in winter the battery runs through to very late in teh evening, so the average price of electricity is generally less than 10 p/kWh. In summer we run off solar power and use teh battery to take us overnight so that we draw nothing from the grid for about 3 months. The cost of this is about £35/month averaged across the year - and £15/month is standing charges! So that covers all the electricity and heating. This article details the costs and covers battery degradation. protonsforbreakfast.wordpress.com/2023/12/30/solar-pv-review-of-2023/ But overall, a battery & solar PV natch very well with a heat pump. Do drop me a line if you have questions. If you want to find out what goes wrong with heat pump installations, try this article. protonsforbreakfast.wordpress.com/2024/02/10/5-reasons-heat-pump-installations-have-problems/ Best wishes Michael

Good Evening. Yes, thanks for your comment which is very important. Roughly speaking, you can use the heating degree days and average gas consumption to estimate the Heat Transfer Coefficient for the house. You can estimate this using daily, weekly or seasonal averages as long as the days weeks or seasons include some cold weather. Suppose the HTC is 300 W/°C. As you say , you want to estimate the heating required on the coldest likely temperature - in my locale that's -3 °C but we actually had -5 °C this year. This is called the design temperature and so if you want to maintain 20 °C inside the house you can estimate that you will require say 23 °C x 300 W/°C = 6,900 W or 6.9 kW. Most people get the heat pump which is the 'next size up' from their estimated maximum demand. Does that makes sense? Best wishes Michael

@@michaeldepodesta001 Thank you for taking to time to reply. Yes absolute perfect sense. Thank you

(I live in different weather conditions and it would be pretty nifty to be able to provide heat and cold with the same system)

@FelipeBudinich Good afternoon. It varies from model to model, but many heat pumps can be run in reverse to provide cooling. However cooling through normal radiators is not very effective. If the flow temperature falls below roughly 10 °C then water will condense on the outside of the radiators - and drip onto furnishings. Instead of radiators, special units are available which maximise heat transfer - similar to the fan-coil units used in air conditioners, but still with water as coolant/