Even with the 'heat island effect' created in built up areas, the research found that the average office will have paid almost £150 more on their bills during the fortnight of freezing temperatures.
The organisation estimated that this added up to an extra £1.2 billion spent on gas and electricity.
Ellie Horwitch-Smith, an energy management expert with Faithful and Gould, said: "As outside temperatures fall, the cold truth is that already inefficient buildings perform increasingly badly as heating systems struggle to maintain the indoor temperatures demanded of them."
She added that the £1.2 billion estimate was "conservative".
Recent research from the consumer group Which? found that poorly insulated homes could see their energy bills rise by 35 per cent by the year 2020.
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