ESTIMATING WATER AND ENERGY SAVINGS

Flow Limiting Valves (FLVs) are made in over 50 different flow rates from 0.4 LPM and above. For showers and basin taps the popular sizes are 4, 5, 6, 8, 9, 10, 12 and 18 LPM. The well proved principle of all our FLVs is based on special rubber control rings installed in precision made housings. The shape and hardness of the rubber ensures that fluid passing through the ring creates hydrodynamic forces such that as the upstream pressure increases, the ring contracts so that the flow remains always the same.

For showers, the chromium plated Marishower suits most applications with its ½” BSP threads to match either the hose inlet or the wall mounting. In the latter case where there is no threaded connection, Flowco Mariflo has a range of insert solutions which fit inside the shower head. The choice of flow depends on the size and style of shower head. In general, the larger the head diameter the higher the flow that will be needed to give an impressive shower. The final choice of reduced flow is down to the Management Team. Flowco Mariflo will supply the appropriate FLV. Having measured the uncontrolled flow, the economic analysis will estimate the overall savings with the reduced flow and the Payback.

Basin taps with spray outlets may be modified by replacing the screwed outlet with the chromium plated Marispray FLV which would normally be set at 4 LPM or the DEFRA recommended 6 LPM maximum. In many instances where the tap has no screwed outlet, a Flowco TopHat type FLV may be fitted into the 15 mm copper tube, down stream of a service valve. Our tests on the basin taps give the flows with the taps fully open but we would not expect occupants always to do this. Instead an assumption is made that the taps are opened to a more moderate 12 LPM. By reducing the maximum flow with a Marispray FLV set to the DEFRA recommended 6 LPM this will save 6 LPM.

ECONOMIC EVALUATION:

Conservative Assumptions:

Room Occupancy 75%;
Guests per room. 1.5;
Showers are run for 5 Minutes per occupant (Dr Hendricks R & D Study 2011 concludes it should be 8 Minutes)
Taps are used for 5 minutes per day per occupant;
Combined Cost of Water, Energy and Sewage Charges at £2.40 per Cub. Metre.

Shower Savings: Typical case of showers reduced from an average 13 to *9 LPM saving 4 LPM
Litres Saved pa. = 0.75 x 1.5 x 5 x 4.0 x 7 x 52 = 8.19 Cub. Metres pa. Per Room
Annual Savings per Room = 8.19 x £2.40 per Cub Metre = £19.65:
*The DEFRA recommendation for showers.

Price of Chromuim Plated Marishower FLV £17.20 each.
Quantity discount for 200+ FLVs in Total = 30%; = £12.04 each

Return on Investment

- 19.65/12.04 = 163%; - Payback period is less than 32 Weeks.

Basin Tap Savings:

Litres Saved pa. = 0.75 x 1.5 x 5 x 6.0 x 7 x 52 = 12.28 Cub. Metres pa. Per Room
Annual Savings per Room = 12.28 x £2.40 per Cub Metre = £29.47:

Price of Chromium Plated Marispray or 15 mm TopHat type FLV £14.20 each
Quantity discount for 200+ FLVs in Total = 30%; = £9.94 each

Return on Investment

- 29.47/9.94 = 296%; - Payback period is less than 18 Weeks.

Combine payback on showers & taps 19.65 + 29.47/12.04 + 9.94 = 223%; - Payback period is less than 24 weeks.
ALSO saving nearly 20 Cubic Metres of water per room p.a.!