Legislation designed to force corporations to cut their electricity bills will affect four times as many construction firms as previously thought

About 20,000 organisations, which could include up to 30 of the largest builders, will have to disclose their usage under the planned carbon reduction commitment (CRC), published on Friday.

Firms that do not disclose information are liable to a £1,000 fine and those that do not provide a “footprint report” must pay an immediate fine of £5,000.

Earlier versions of the document had only mentioned the 5,000 companies with electricity bills of more than 6,000MWh per year. The government had originally estimated that seven construction firms would be liable to take part in the scheme. Now, any organisation with a peak load greater than 100kWh will have to calculate how much electricity it has used.

Participants must buy permits to cover emissions, first at a fixed price of £12 a tonne from 2010 and then through auctions from 2013 when fewer permits will be available.

Eluned Watson, solicitor with law firm Pinsent Masons, said the CRC was complex, but would reward construction firms who addressed energy efficiency measures.