The green deal provider must make a reasonable estimate of the period over which each improvement is likely to result in annual savings on energy bills which are equivalent, after taking into account the effect of likely changes in the price of energy, to the improvement-specific first year savings for that improvement.

Subject to paragraph (4), the green deal provider must, when making the estimate under paragraph (2), include any period when the efficient functioning of the improvement is likely to depend on repairs for expected wear and tear.

The period included under paragraph (3) does not extend beyond the time that the green deal provider estimates that the likely cumulated cost of carrying out repairs for wear and tear will exceed the likely cost of replacing the improvement.

The savings period is the longest of the periods estimated under paragraph (2).

The estimate made under paragraph (2) is, in relation to an improvement, the “improvement-specific savings period”.