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Site overview

A newly built Adult Learning Centre in Croydon.


The Problem

  • The building design included a ground source heat pump coupled to thermostatically controlled, zoned under-floor heating systems. Two small industrial boilers had also been installed to provide LPHW supplying radiators for perimeter heating.

  • A review of both systems suggested that the heating activity in the building was mainly being done by the Low Pressure Hot Water (LPHW) system. All of the radiators were found to have their Thermostatic Radiator Valves (TRVs) turned to maximum.

  • The TRVs had been turned to maximum, whilst a fault with the under-floor heating system was being corrected. However, the TRVs were never returned to their previous setting.

Adjusting Temperature

The Solution

  • All radiator TRVs were turned down from the maximum setting to a setting of 19°C; then subsequently fixed to prevent tampering.

  • The software trigger for both systems was modified to create a “dead band”, so that the under-floor system was enabled before the LPHW radiator system, whereby the perimeter heating system was used as a back up, rather than the primary source of heating within the building.

  • The theoretical return on investment on this modification was calculated to be in the region of four months. The actual measurement of the savings established through the analysis of site consumption data (from utility metering) however, was under two months.

Measurement of Savings Achieved

  • Annual Energy Reduction = 150,000kWh

  • Annual CO2 Reduction = 28 tonnes

  • Annual Cost saving = £3,000

  • Cost of implementation = £500

Return on Investment

Payback period = 2 months


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