How right must you be?

What level of skill and care is required of you when you are designing a project? Must you be perfect? Must you know everything? You may be surprised at the wide application of the legal principle which provides the answer.

Mr Z (not a building services engineer) was sentenced to a prison term after threatening two people with an imitation firearm. After a violent incident in prison involving Mr Z and a member of prison staff, he was placed in a single cell, and was seen by a prison psychiatrist on several occasions.

The psychiatrist concluded that Mr Z was not depressed. Sadly, Mr Z hanged himself in his cell the day after one of his appointments with the psychiatrist. His widow made a claim against the Home Secretary, insisting that other measures should have been taken.

What has this unfortunate sequence of events to do with building services? The answer is that the level of care and skill required of you when you are designing a project is determined in the same way as was the level and care and skill which the court required of the prison psychiatrist (or which the court would require of, say, a lawyer).

Setting a standard
The standard is, what would a reasonably competent prison psychiatrist (building services engineer), applying the standards prevailing at the time, have done under the circumstances? If there is more than one possible answer, was there a respectable body of opinion within the psychiatric (or building services engineering) profession which would have done what the prison psychiatrist (or building services engineer) in fact did? In Mr Z's case, the court heard expert psychiatric evidence, some of which suggested that the psychiatrist should have realised the suicide risk, but some of which suggested that what the psychiatrist had done (or not done) was appropriate. The court (in December 2000) decided that there were two eminent (although opposing) bodies of opinion before it, and the prison psychiatrist had not followed what was described as an "extraordinary" course of action. The widow's claim subsequently failed.

In Hammersmith Hospitals NHS Trust v Troup Bywaters & Anders (TBA), in May 2001, the Court of Appeal had to deal with a situation on a very limited ground about the precise meaning of an expert's reply to one particular question in court – which reply we need not concern ourselves with.

The case was about two dual-fired waste incinerators, which were required to burn 250 kgs of clinical waste per hour, while producing emissions of carbon monoxide not exceeding 100 mgs/m³ averaged over an hour. This throughput rate was allegedly never achieved, and the specified carbon monoxide emission limit was allegedly exceeded. TBA had advised on the incinerators. They were described by Lord Justice Dyson in the Court of Appeal as "a firm of general practitioner mechanical and electrical building services consulting engineers. They are not specialists in combustion, incineration or waste management technology."

Obvious targets
Since the manufacturer (Erithglen Ltd) went into receivership a year or so after the incinerators were installed, they were the obvious target for the disappointed hospital trust. It was alleged that TBA should have given different advice to its client.

Prior to the acceptance of Erithglen's proposals for the site, TBA had obtained from Erithglen an assurance of compliance and an independent report which indicated some problems with the running of the proposed boilers on another site. TBA forwarded the report to an engineer at the hospital trust. Queries raised by the trust were forwarded to Erithglen, which gave detailed explanations as to how the problems identified had been solved.

The judge concluded that, based on the information available to TBA, what TBA did was what "a reasonable body of the profession" would have done. Accordingly, the hospital trust's claim failed. On appeal, it was not disputed that this was the appropriate test – instead what the trust tried to argue was that this test had been wrongly applied in view of what the trust's expert had previously said.

The Court of Appeal found little difficulty in disposing of the appeal. It was satisfied that the expert's reply meant what the judge had thought it meant. The Court of Appeal also noted that the Judge (who had heard ten engineers giving evidence of fact and two giving expert evidence) had taken into account the facts that the manufacturer had been considered to be reputable, and that the TBA engineer in question was conscientious, competent and a truthful witness.

Additionally the judge noted that performance tests were required before acceptance of the incinerators was possible, and that Erithglen's explanations of the problems at the other site sounded reassuring.

He also observed that there had been no prior knowledge or suspicion of underperformance of the incinerators at a third site which was visited by TBA. The expert for the trust had previously written reports about the possible installation or upgrade of the same type of incinerator at other hospitals which did not suggest that carbon monoxide emissions were a problem.

Clause for thought
The usual standard expected of a building services engineer, or of any professional, does not involve omniscience and perfection. However, a clause in the contract of engagement could require such a high level of achievement, although it is unlikely to be described in this particular manner.

In particular, watch out for fitness for purpose clauses, or guarantees. Watch out, too, for words such as 'ensure' or 'procure'. Furthermore, if the engineers in this case had held themselves out as waste incineration specialists – which they did not – a higher than usual standard (although not infallibility) would have been expected.