Regulation 5 Calculations of the number of therms supplied on the basis of actual calorific values of gas supplied

(1)

The number of therms supplied by a relevant supplier to a customer during a relevant charge period shall be calculated in accordance with the following formula:

number of therms supplied = \frac{A \times B}{105.5}

where

A is the number of cubic metres of gas supplied to the customer during the relevant charge period, and B is the relevant calorific value of the gas supplied to the customer during such period.

(Note: Where gas is supplied through a meter measuring in cubic feet, the number of therms supplied can be ascertained by multiplying the number of cubic feet of gas supplied by the number of megajoules in the relevant calorific value and dividing the product by 3730.)

(2)

The relevant calorific value of the gas supplied to a customer during a relevant charge period shall be calculated by aggregating the relevant area average calorific values attributable to each relevant seven day period (except the first such period) the whole or part of which falls within the relevant charge period, and dividing the aggregate so obtained by the number of periods in respect of which a value is aggregated, but so that in calculating the relevant calorific value of the gas supplied to the customer during the relevant charge period–

(a)

no account shall be taken of any amount of less than 0.1 megajoules per cubic metre;

(b)

where the relevant declared calorific value for the relevant charge period exceeds 35 and does not exceed 45 megajoules per cubic metre, the relevant calorific value shall not exceed a maximum of 0.8 megajoules per cubic metre above the relevant declared calorific value; and

(c)

where the relevant declared calorific value for the relevant charge period either does not exceed 35 or exceeds 45 megajoules per cubic metre, the relevant calorific value shall not exceed a maximum of 2% above the relevant declared calorific value.

(3)

Where measurement directions require that actual calorific values of the gas supplied in an area are determined at one measurement place, the area average calorific value attributable to any relevant seven day period shall be calculated by aggregating the actual calorific values determined in accordance with the directions, or, if either regulation 6 or regulation 7 below applies, deemed to be determined in accordance with that regulation, at that place in respect of the gas supplied in the area in question on each day falling within the period of seven days ending at midnight on the Wednesday preceding the relevant seven day period, and dividing the aggregate so obtained by seven.

(4)

Where measurement directions require that actual calorific values of the gas supplied in an area are determined at more than one measurement place, average calorific values attributable to any relevant seven day period shall be calculated in respect of each measurement place, in the manner provided in paragraph (3) above as respects a single measurement place, and the area average calorific value attributable to the period shall be–

(a)

if the calculations in respect of the different places result in different averages, the lower or lowest (as the case may be) of the averages so calculated;

(b)

if the calculations result in the same average, that average.

(5)

In calculating any maximum under paragraph (2) above, or any average calorific value under paragraph (3) or (4)–

(a)

no account shall be taken of any amount which is less than 0.05 megajoules per cubic metre, and

(b)

any amount of less than 0.1 but not less than 0.05 megajoules per cubic metre shall be treated as if it were equal to 0.1 megajoules per cubic metre.