English Heritage has attacked the environmental credentials of the Land Securities ‘Walkie Talkie’ tower in the City of London on the first day of the public inquiry into the development.

Cross-examining the architect Rafael Vinoly this afternoon, English Heritage’s QC Robert McCracken said ‘It doesn’t appear that very much thought has been given to these matters’.

McCracken spent more than an hour pressing Vinoly on environmental aspects of the scheme at 20 Fenchurch Street.

The building features 322,290 sq ft (33,000 sq m) of glazed facades and would use 21 million kilowatt hours of electricity a year to keep it cool, McCracken said.

In an earlier presentation, Vinoly said external shading would be used to reduce solar gain and that the design team was close to meeting the Mayor of London’s requirement for 10% renewable energy generated on-site. He told McCracken that low and zero-carbon technologies were ‘a concern for the design’.

Russell Harris QC, representing Land Securities, protested that English Heritage had not raised environmental concerns in its proof of evidence prior to the start of the inquiry. Hilson Moran, the scheme’s engineers, may now be called as witnesses.

The 37-storey tower is subject to a two-week public inquiry after being called in by secretary of state Ruth Kelly in November.