Significant CO2 and gas savings at Norwich Union

Case studies

Published: 17 March

Author: Alan O'Brien

Type: Case studies

Year: 2009

An initial pilot project using Sabien Technology’s M2G intelligent boiler load optimisation technology at three Norwich Union sites over the 2007-2008 winter heating season delivered significant savings in energy and carbon emissions. A subsequent estate wide rollout was commissioned.

When Norwich Union (part of AVIVA) set itself a target of reducing gas consumption by 5% in 2008, one of the key areas the company looked at was the performance of its boiler plant.

“As part of AVIVA’s CSR policy we are committed to sustainability and one element of this is to focus on our use of resources,” explained Norwich Union’s Energy & Utilities Manager Gregory Luxford. “A number of technologies that claim to improve boiler efficiency were investigated and, following a pilot trial, Sabien’s M2G was selected for installation across Norwich Union’s UK estate.

The three sites for the pilot were chosen by Norwich Union as representing a cross-section of the company’s portfolio. The pilot, which was managed by Sabien, was conducted for 30 days at each site between January and March 2008. During this time gas consumption and associated carbon emissions were reduced by between 14% to 17%, with an average of 15% across the three sites. The average payback was only 50 weeks, with annual CO2 savings of 76 tonnes.

As the pilot was carried out during the colder months of the year, when boilers were operating at high capacity, Norwich Union expects to achieve even higher proportionate savings during periods of higher ambient temperature when the boilers will be subject to increased dry cycling.

Boiler load optimisation

Intelligent boiler load optimisation is able to differentiate between a genuine need for heating in a building and a call for the boiler to fire simply to compensate for standing heat losses from the boiler itself.

During the pilot, M2G units were retrofitted to each of the pilot boilers where the flow and return water temperatures are monitored every 10 seconds. Each time a call for heat is made, the M2G automatically checks the latest data it has stored and decides whether it is a genuine demand from the building/BMS or whether the boiler is firing because of standing (heat) losses.

Crucially, M2G automatically references the thermostat set points to ensure that room and hot water temperatures are unaffected during pilot operation and that there was no compromise to the buildings’ comfort levels.

In order to create an accurate comparison, Sabien’s pilot methodology is to configure the M2G to operate in ‘Save’ mode on one day and ‘Bypass’ mode the next day. In Save mode the M2G is operational and makes savings. In Bypass mode, the M2G is bypassed and makes no savings.

Industry standard degree day calculations are then carried out to compensate for variation in daily ambient temperatures during the pilot period, so the comparison between Save days and Bypass days is accurate and meaningful.

“The pilot project delivered very impressive results and enabled us to make a strong business case for rolling out the M2G technology across a further 30 properties on the estate,” Luxford recalled. “The roll out was completed early in 2009 and we are now in the process of measuring boiler performance at all of the M2G sites to confirm the savings that have been achieved,” he continued.

Smooth delivery

Given the scale of the Norwich Union estate, Sabien’s ability to manage this £188,000 project, covering an area from the North of Scotland to the South West of England, was a key criterion. Working closely with the Norwich Union management team, a schedule was developed and communicated to building managers to arrange access and ensure there was no disruption to the staff working in the buildings.

“In a project of this nature a good working relationship is vital. We found Sabien to be very responsive and very practical in their approach and this was a major contributor to the smooth delivery of the project,” Luxford concluded.

As featured in Water, Energy and Environment - February / March 2009