[{"data":1,"prerenderedAt":147},["ShallowReactive",2],{"resource-/resources/two-estates-one-spreadsheet":3},{"id":4,"title":5,"audience":6,"author":6,"body":7,"category":127,"date":128,"description":129,"draft":130,"extension":131,"image":6,"imageAlt":6,"meta":132,"navigation":133,"ogImage":134,"path":135,"pdfPath":6,"resourceType":6,"seo":136,"series":6,"stem":137,"tags":138,"visibility":145,"__hash__":146},"resources/resources/two-estates-one-spreadsheet.md","Two Estates, One Spreadsheet",null,{"type":8,"value":9,"toc":116},"minimark",[10,14,17,24,29,32,35,38,41,45,48,51,54,57,61,64,67,71,74,77,81,84,87,90,94],[11,12,13],"p",{},"Two estates in the same English city, a few miles apart. Both mostly social rented, both mostly post-war, both the kind of stock that reaches a board as a single row: number of homes, average band, tenure split, an indicative cost. Read that way they are the same problem twice over. Priced home by home, they are not the same problem at all.",[11,15,16],{},"We compiled both from the public record, 383 homes on the first estate and 313 on the second, every home carrying its own record of what it is and what it uses. Then we costed the same work into each one, a fabric package with a heat pump in every home, and put a single question to each home. Does it pay back inside fifteen years?",[11,18,19],{},[20,21],"img",{"alt":22,"src":23},"Comparison card: two estates, same on a spreadsheet, opposite investment answers when priced home by home.","/images/resources/articles/two-estates-one-spreadsheet-1600x900.png",[25,26,28],"h2",{"id":27},"what-the-record-found","What the record found",[11,30,31],{},"On the first estate, 91 homes do. On the second, two.",[11,33,34],{},"The gap is not condition, and it is not age. What separates the two is what the homes burn. The first estate is mixed, and about a third of its homes are heated by electricity at a unit rate roughly four times gas, so taking that heating out and putting a heat pump in takes a large bill down a long way. The second estate is on mains gas almost throughout. Every one of its 191 social-rented homes is. Against gas at today's price the same heat pump saves much less, and the case for it is a carbon case rather than a bill case.",[11,36,37],{},"The two homes that do clear fifteen years on the second estate are the only two on it heated by electricity.",[11,39,40],{},"Neither of those findings would survive a stock spreadsheet. Both estates look perfectly ordinary in one.",[25,42,44],{"id":43},"then-we-moved-the-price","Then we moved the price",[11,46,47],{},"An estate that pays for itself at today's prices is one thing. What matters to anyone signing a business case that runs for thirty years is what happens when the price moves, so we re-priced both estates under illustrative price futures, taking the gas price from today up to double and letting electricity follow at a bit over half the gas move. These are not forecasts. They are positions, used to find out how much of each answer depends on the price of gas rather than on the homes themselves.",[11,49,50],{},"The first estate barely notices. Ninety of its 91 qualifying homes are heated by electricity, and a rising gas price does very little to a home that does not use gas: sweep gas all the way to plus 120% and that group has grown only to 99. The estate's count does climb, from 91 to 154 across the range, but almost all of that comes from its own gas-heated homes, which start at none. It is really two estates inside one boundary, a price-proof core and a gas-exposed remainder, and only one of them is waiting on the market.",[11,52,53],{},"The second estate does not drift upward. It flips. Sixty-seven homes cross the fifteen-year line inside a single ten-point move in the gas price, somewhere between plus 60% and plus 70%, and by the top of the range the count stands at 125. The cause is worth stating carefully. On today's public record many of these homes are near-identical: the certificates describe the same size, the same construction and the same heating, so the record prices them within pounds of one another and they reach the threshold together. Some of that sameness is real, and some of it is the resolution of certificate-level evidence.",[11,55,56],{},"Either way the consequence for a programme is binary: order the work at today's prices and the order is either far too small or far too large, and you find that out in one go. Better per-home evidence is what turns a step like that into a slope you can plan against.",[25,58,60],{"id":59},"where-the-money-already-is","Where the money already is",[11,62,63],{},"Inside the first estate is a cohort that needs none of this to be true. Its 107 social-rented homes on electric heating are 28% of the place and carry 70% of the whole saving, and they pay back in around nine years, indicative, against roughly twenty to twenty-seven years for treating all 383 homes together. The same programme, aimed at the homes the record picks out, pays back in well under half the time.",[11,65,66],{},"That cohort is where a first phase goes, and it is settled at today's prices. The rest of the first estate, and very nearly all of the second, is a decision about what you expect the price of gas to be in year eight.",[25,68,70],{"id":69},"what-actually-decides-it","What actually decides it",[11,72,73],{},"One result from the same exercise is worth more than the headline. On the second estate, a future in which gas rises 50% and electricity rises 30% moves very few homes inside fifteen years. A future in which gas rises only 30% while electricity falls 10% moves many times more. The counts themselves are soft in that part of the range, because the homes are bunched and the answer shifts with the capital cost assumption, but the direction is not soft at all. The smaller gas rise does more work, because what decides whether a gas-heated home is worth converting is the distance between the two unit prices rather than the gas price on its own. That distance is a little over four today, and it narrows to three in the second case.",[11,75,76],{},"Most business cases are stress-tested against a gas price going up. Very few are tested against an electricity price coming down.",[25,78,80],{"id":79},"where-this-leaves-you","Where this leaves you",[11,82,83],{},"Neither landlord sent us anything. Both estates were compiled from records that are already public, before any conversation, and the same can be done for any place in England.",[11,85,86],{},"If you are sizing a programme this year, are you pricing your stock at today's rates, or at the rate you expect to be defending in year eight?",[88,89],"hr",{},[25,91,93],{"id":92},"about-the-numbers","About the numbers",[95,96,97,101,104,107,110,113],"ul",{},[98,99,100],"li",{},"Both estates are de-identified deliberately. The finding is about how two ordinary estates differ, and naming them would turn it into a story about two landlords.",[98,102,103],{},"Every figure is indicative, compiled from the public energy certificate register and open location data. Nothing was measured, no home was visited, and no resident information is used or inferred. None of it is an investment recommendation.",[98,105,106],{},"Payback uses the mid-point of each home's sourced capital cost range, gross of any grant. The low and high ends of that range move the counts, and they move them furthest in the middle of the second estate's range, where the homes are bunched. Any single count taken from that region should be quoted with its band.",[98,108,109],{},"Price futures are illustrative positions, not forecasts. Electricity moves at 0.55 times the gas move, on the basis that a majority of marginal power in Great Britain is still set by gas. Held flat instead, electricity produces a much earlier crossing, which is why a flat-electricity figure should never travel without that qualifier.",[98,111,112],{},"The cohort payback of around nine years uses all 107 homes and the mid-point of each home's cost range. Twelve of the 107 already have an air source heat pump from earlier works; the package as modelled still installs one in every home, so those twelve carry cost while returning almost no saving. Excluding them, the cohort pays back in around eight years. The figure is also the one most exposed to the flat single-rate electricity assumption: most of these homes use direct-acting room heaters, where a restricted-hour tariff is common and would change both the starting bill and the saving.",[98,114,115],{},"Simple payback throughout. No discounting, no carbon price, no maintenance difference, no residual value, and each future is held constant rather than run as a path.",{"title":117,"searchDepth":118,"depth":118,"links":119},"",3,[120,122,123,124,125,126],{"id":27,"depth":121,"text":28},2,{"id":43,"depth":121,"text":44},{"id":59,"depth":121,"text":60},{"id":69,"depth":121,"text":70},{"id":79,"depth":121,"text":80},{"id":92,"depth":121,"text":93},"articles","2026-07-28","Two social housing estates in the same English city, compiled from the public record and priced home by home. At today's prices, 91 homes on one estate pay back a whole-home retrofit inside fifteen years. On the other, two do.",false,"md",{},true,"/images/resources/articles/two-estates-one-spreadsheet-1200x627.png","/resources/two-estates-one-spreadsheet",{"title":5,"description":129},"resources/two-estates-one-spreadsheet",[139,140,141,142,143,144],"housing and place","retrofit planning","social housing","heat pumps","fuel poverty","investment planning","public","SSb0RWYoGdmWL_2fGB_Eq47vugh2QINmCLlqxnfVnso",1785236269896]