# When calculating the reduction in delay damages, should the actual or assumed benefits be used?

When calculating the reduction in delay damages, should the actual or assumed benefits be used?

When calculating this proportion, the actual benefits known at the time of the calculation should be used, not those assumed when the delay damages were originally calculated. For example, a contract is for the construction of a factory which builds products A and B. This has separate buildings with production lines for each product and the Employer calculates that he will make £5,000 per day profit out of product A and £3000 out of B. He decides that he wants Completion of both buildings to occur together and therefore sets the delay damages at £8,000. However, the Employer takes over one of the buildings first and starts making product A. Meanwhile, the market price for both products has changed to £4000 out of Product A and £5,000 out of type B (total now £9,000). The proportion of the new benefit of the part of the works still to be taken over to the new benefit of all of the works is now £5000/£9000 ie five ninths. This proportion is then applied to the original level of the delay damages to provide the following delay damages for the remaining part of the works not yet taken over

£8000 * 5/9 = £4,444