Energy scandal: misleading efficiency claims leading to huge bills for homeowners

Sarah Knapton
New homes are often not as efficient as older houses  -  Ivan Smuk / Alamy

Homeowners and companies are being hit with unexpectedly high energy bills because planners continually make false promises about the 'green' credentials of new buildings, a major study has found. 

Thousands of new homes, schools and offices are using double the energy that they should because planners are massively overestimating their efficiency, the University of Bath has found.

Britain’s buildings account for nearly half of the nation’s greenhouse gas emissions through heating, cooking and lighting, but a new study suggests that carbon dioxide levels could be slashed if structures acted as they did on paper.

Experts at Bath University likened the scandal to the VW emissions debacle, where thousands of cars were fitted with defeat devices to beat rigorous pollution testing.

The government is aiming to cut greenhouse gas emissions by 34 per cent by 2020, and 80 per cent by 2050, but researchers say targets will be missed if builders continue to misinform clients about how efficient their homes and offices will be.

The difference between how much energy a building is predicted to use and how much it uses in reality has been known in the industry for decades, and is dubbed the ‘performance gap.’ But architects and engineers have traditionally blamed the problem on faulty construction, or unexpected use after completion - such as owners leaving too many lights on.

Half of Britain's greenhouse gas emissions are caused by buildings, but they are using double the amount of energy than they should  Credit: ALI HAIDER

However David Coley, Professor of Low Carbon Design at the University of Bath, said the real problem stemmed from the practice of building modelling, which is not ‘fit for purpose.’

“It’s a serious scandal,” he said. “It affects all new buildings as well as the refurbishment of older ones.

“When one school in Plymouth was rebuilt, the energy bills for a month ended up costing the same as for an entire year in the old 1950s building.

“The problem is nobody checks that the building is performing as promised. There is very little regulation. They can't be sued. It’s like a surgeon not being bothered about whether their patient lived or died.

“The impact of the inaccuracies of building modelling professionals has severe financial and environmental implications for both the government’s global warming targets as well as building owners who are purchasing homes and other buildings that are sold to be energy efficient but in reality are not.”

In the first research of its kind, a team from Bath’s Department of Architecture & Civil Engineering and Department of Psychology interviewed 108 building modelling professionals about 21 common design energy-related aspects of a building, from the insulation in the walls to the temperature the heating was set to.

The questioning was based on a real building in which detailed energy, occupancy and temperature data had been recorded, and provided a comparison with the answers of those surveyed.

New buildings and refurbishments are usually far less efficient than promised in the original design Credit: PA

The researchers found that the building modelling professionals could not agree on which aspects were important and which were not, or how much difference to the energy bill changes to them would make. A quarter of those interviewed were judged to be no better than if a member of the public had responded at random.

Building modelling professionals are responsible for forecasting a proposed building’s energy efficiency and making recommendations about which design aspects achieve the highest possible building performance in terms of energy efficiency.

They use a number of computer simulation programmes whereby they input data about the proposed building to calculate the building’s energy efficiency, indicated by the building’s Energy Performance Certificate.

However, unlike car and washing machine manufacturers, building modellers are not legally obliged to ensure a building’s certificate matches its performance in real life.

Co-investigator and Senior Lecturer in the Department of Psychology, Dr Ian Walker added: “Given our findings about how the level of relevant education and experience don’t separate the good modellers from the bad, we are calling on the government for educational and policy change to work with industry and universities to increase efforts in improving building physics education.

“Currently, an in-depth qualification for building modelling does not exist, meaning there is little formal training process for those entering the profession. If this aspect can be addressed, part of the ‘performance gap’ could rapidly be reduced.”

The Blame Game

The UK Green Building Council said the government should bring in certification for homes that meet energy standards.

John Alker, Director of Policy & Campaigns at the UK Green Building Council said: “ “There is no doubt that the majority of buildings do not perform as they were designed to do. This is widely known in the construction sector, and it is something that the industry needs to get to grips with.

“The so-called ‘performance gap’ occurs for a variety of complex reasons, and needs action by all those involved in the property life cycle – such as architects, engineers, contractors and facilities managers – not just building modelling professionals.

“Government could support this by mandating Display Energy Certificates for all buildings, which show how a building actually performs in operation.”

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