By David Strahan
A small British startup has withdrawn from the market for measuring heat loss from new homes after legal threats from a subsidiary of one of the world’s biggest insulation manufacturers.
In November, Saint-Gobain Isover, a subsidiary of Saint-Gobain, threatened to serve Redbarn Group with an injunction, and to sue for damages and costs, unless the startup agreed to withdraw Veritherm, its heat-loss measuring system.
Last week, Redbarn wrote to Saint-Gobain to capitulate, leaving Saint-Gobain’s system, QUB (‘cube’), as the sole method of cheap and rapid pre-occupancy heat-loss measurement available to UK housebuilders, according to experts in the field.
Measuring heat loss will be vital to ensure that housebuilders meet the strict efficiency and emissions rules planned for 2025 so the UK achieves its net-zero targets.
Redbarn’s withdrawal from the market comes just weeks after independent test results were published that indicated that Veritherm is more accurate than QUB.
High costs
New homes in the UK are typically less energy efficient than their builders claim – sometimes the heat losses are more than double.
This is known as the ‘performance gap’. The Future Homes Standard, which comes into force in 2025, will oblige housebuilders to prove their homes emit 75 per cent less CO2 than those built under current rules, meaning they must be far more thermally efficient.
The gold standard of heat-loss measurement in an unoccupied home is known as the ‘coheating test’, but this takes three weeks and costs around £8,500 per home tested, according to academic research.
QUB and Veritherm both heat an empty home to high temperatures and then monitor internal and external temperatures to calculate the heat loss over a single night.
Since these overnight tests are so much quicker and simpler than coheating, they are also far cheaper – Veritherm’s prices started at £500 per home.
Other companies such as Build Test Solutions can also measure heat loss cheaply, and without heating the property to high temperatures, by using unobtrusive sensors and incorporating data from a smart meter.
But this ‘passive’ method requires the home to be inhabited and takes around three weeks to complete.
Patent claims
Saint-Gobain claimed that Redbarn, a family-run firm based in Hereford, infringed two patents granted to it in 2017 and 2018. Redbarn’s Veritherm technology is protected by a patent granted in 2021.
Redbarn denies Saint-Gobain’s claims but has suspended all Veritherm business because it says it cannot afford to defend the issue in court, which it has been advised could cost up to £400,000.
The British firm has raised less than £2m in private investment and government grants since it was founded in 2018 while the multinational turned over €51bn (£43.6bn) in 2022.
Lord Deben, the recently-retired chair of the government’s Climate Change Committee, said: “This is not David vs Goliath, but Goliath vs David with his hands tied behind his back”.
Clare Fenton, a director of Redbarn Group, said: “Closing down Veritherm means five years of hard work, innovation and investment down the drain. It’s pretty much our entire business gone.”
The legal threat came after a year of collaboration between the two companies.
In November 2022, Redbarn and Saint-Gobain worked with two other companies to demonstrate heat-loss testing in 20 homes built by four major housebuilders.
Redbarn also allowed BSRIA, a building testing company which is also Saint-Gobain’s delivery agent for QUB in the UK, access to Veritherm equipment and software for evaluation purposes.
Another project took place in a state-of-the-art testing facility called Energy House 2.0 at the University of Salford, where two housebuilders each built an energy-efficient house inside the atmosphere-controlled hangar and their heat losses were measured using both QUB and Veritherm.
The construction of one of the houses was funded by Saint-Gobain and Barratt Developments, the UK’s biggest housebuilder. Saint-Gobain agreed to Salford’s plan to test Veritherm in the house alongside QUB.
Preliminary results from the Salford trial published on 2 January showed that Veritherm produced a more accurate central measurement of the heat loss than QUB. Compared to the ‘gold standard’ coheating test, QUB was 15 per cent lower and Veritherm 6 per cent lower (see graph, below).
Veritherm’s ‘uncertainty interval’, indicated by the black bars in the chart, was wider than QUB’s.
But even at the extremes of its uncertainty interval, Veritherm’s calculations are closer to the central coheating measurement than those of QUB. Veritherm’s uncertainty interval overlaps with that of coheating whereas QUB’s does not.
QUB and Veritherm measurements of heat loss, known as ‘heat transfer co-efficient’ or HTC, compared to the gold-standard coheating benchmark.
Saint-Gobain’s lawyers, Murgitroyd, wrote to Veritherm in November 2023 threatening to take “all necessary action” unless Redbarn signed a letter committing to cease all business relating to Veritherm,“deliver up or destroy” all Veritherm equipment, reveal extensive commercial information and pay Saint-Gobain damages and costs.
“I don’t understand why Saint-Gobain would take this action after working alongside us for almost a year, and long after our patent was granted,” said Fenton.
The two companies’ technologies may appear similar but they use different mathematical models to calculate the heat loss, both of which have been published with their patents.
Saint-Gobain has made 25 claims of patent infringement against Redbarn, many of which relate to its use of standard equipment such as temperature sensors, electric heaters or computers, which Redbarn maintains are ‘prior art’ that cannot be patented.
Other claims are based on test results previously published on the Veritherm website, which Saint-Gobain alleges must have come from its own calculation method. Redbarn insists that any similarity is coincidental.
Less choice
The withdrawal of Veritherm leaves housebuilders with fewer options to measure heat loss in recently completed homes before they are sold. Coheating is expensive and takes three weeks. Passive techniques are the cheapest but also take three weeks and usually require the property to be occupied. Overnight testing is quick and economical, but now QUB is believed to be the only service available in the UK.
Several industry sources confirmed that QUB and Veritherm had been the only overnight heat-loss-testing technologies available in the UK. David Adams of the Future Homes Hub, a government-backed initiative to help builders reach net zero, said “there are two so far” but added “there is a lot of activity in this space”.
An executive at a major housebuilder, who spoke on condition of anonymity, was dismayed at the withdrawal of a product from the market. “It’s rare for a reduction in competition to be a good thing because it kills off innovation and the price could go up,” he said. “So I would say it’s bad news”.
Professor Richard Fitton of the University of Salford, who oversaw the Energy House 2.0 trial, would not comment on the legal dispute but said: “I would rather see many, many companies testing buildings. It’s always better to have a market.”
The housebuilder executive said that the passive technologies that take three weeks were an unsatisfactory alternative to overnight testing because they would not satisfy the industry’s typical delivery schedules, which are governed by the New Homes Quality Code. “Three weeks is a long time to have a £300,000 house just sitting there. It really needs to be an overnight test.”
As things stand, Redbarn has been forced out of the very market it says it has played a leading role in developing. Redbarn has been offering Veritherm commercially since 2019, whereas Saint-Gobain launched QUB in the UK, through BSRIA, in 2023.
Based on current housebuilding rates and Veritherm’s published pricing, the pre-occupancy heat-loss-testing market in the UK could in future be worth more than £100m per year if the government requires heat loss certification for every home built.
Investigation calls
Lord Deben has called on the Secretary of State for Energy Secretary and Net Zero, Claire Coutinho MP, to instruct government lawyers to investigate and if necessary call in senior executives from Saint-Gobain to find a solution.
In a statement, the French firm said: “Saint-Gobain invests significant resources in bringing new innovation to market driven by a desire to help customers solve problems and support the development of light and sustainable construction.
“Our patented QUB® technology has undergone significant development, in-situ testing in the UK and Europe and continues to be piloted with a number of UK housebuilders and in our research project with the University of Salford and Barratt Developments at Energy House 2.0.
“It is an important innovation for the future development of more sustainable construction which allows builders and developers to assess the heat loss of buildings quickly and accurately.
“We wholly support strong competition which will help this growing market.”
Saint-Gobain did not respond to a question from Construction News on whether the firm now considers the matter closed.
This is not the first time a Saint-Gobain subsidiary has been embroiled in controversy. A former employee of Celotex, another Saint-Gobain company, told the Grenfell inquiry that the firm had been “dishonest” by “over-engineering” safety tests of its RS5000 insulation.
The foam was used in cladding on the tower, which caught fire in 2017, a blaze that killed 72 people.
The product was withdrawn from the market nine days after the tragedy.
A statement on Celotex’s website says that the firm’s current management was unaware of issues “concerning the testing, certification and marketing of Celotex’s products”.
It says: “These matters involved unacceptable conduct on the part of a number of former employees, that was not in line with Saint-Gobain’s values. They should not have happened. Disciplinary proceedings were instituted as a result and six employees left the company (others having resigned previously).”
