Dissenting Opinion by
Judge Craig :The order of the Pennsylvania Public Utility Commission (PUC) should be reversed insofar as it prohibits the master metering of electricity in all new “multi-tenancy commercial buildings” because the record lacks substantial evidence to show that the proposed tariff rule would achieve energy conservation, and, consequently, the only purpose and effect of the proposed tariff modification is to enlarge the utility’s revenues by necessarily reducing the number of opportunities for customers to benefit from volume discounts.
1.
Where the PUC investigates a public utility’s proposed modification of its rates or regulations, the pub-*314lie utility has the burden of proving the reasonableness of the modification. 66 Pa. C. S. §315. Pennsylvania Power and Light Company (PP&L) asserts that its proposed prohibition of master metering, and resultant promotion of individual metering, will produce energy conservation by causing tenants to learn their true energy costs and thus be motivated to reduce their energy consumption.
Even if the truth of that assertion is assumed, PP&L has nevertheless failed to demonstrate a rational relationship between its stated goal of energy conservation and its proposed comprehensive ban of master metering which would encompass buildings whose tenants are submetered and thus apprised of their energy costs. To the contrary, PP&L’s expert witness testified that the electric consumption/oonservation of submetered tenants would be proportionately equivalent to the electric consumption/conservation of individually metered tenants if both groups were billed at the same rate, i.e., had proportionately identical costs. Because PP&L did not offer any evidence of differences in the billing rates of individually metered and submetered tenants, PP&L did not meet its burden of proving that its proposed tariff rule would achieve the avowed goal of energy conservation.
2.
With the alleged energy conservation purpose absent, the result of the proposed master metering prohibition is obviously to eliminate the volume discount savings which the commercial center operator can receive as a result of master metering, and, depending upon leasehold bargaining, may or may not share with tenants.
A tariff change which produces additional revenue not shown to be required to provide a reasonable return to the utility, and which has only the effect of *315shifting economic benefit from ratepayers to the utility, cannot properly be approved by the PUC, nor should such an approval be affirmed by this court.
Judge Blatt joins in this dissent.