HVAC retrofit in the Scottish Parliament building led to significant energy savings

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Overview

The Scottish Parliament is dedicated to reducing both carbon footprint and energy bills, Environmental Performance Manager David Fairhurst has already made significant improvements to the buidling in recent yearshaving already achieved a reduction in carbon emissions of 25%. Following a presentation by ebm-papst UK on energy savings possible on existing HVAC equipment by upgrading to EC fans, Mr Fairhurst approached ebm-papst UK and asked for a survey to be carried out on the Parliament Building’s HVAC equipment.

ebm-papst UK identified the HVAC equipment that would offer the greatest potential for energy savings, and by working together with the original equipment manufacturer, Airedale was able to provide the best solution. It was decided that the computer room cooling offered the best potential for energy savings, therefore an initial trial was carried out on one Computer Room Air Conditioning (CRAC) unit; following excellent results on the initial trial unit, further installations have been carried out on both CRAC and Air Handing units (AHU’s).

The Scottish Parliament is committed to reducing it’s carbon emissions by more than 40% by 2020. To achieve this we need to reduce electricity
use by at least 40%. ebm-papst UK
claimed that it’s fans would deliver at least this level of reduction and this claim has proven to be true. EC fans are a step change technology, much like LED lighting, which has been a very welcome addition to our carbon management plan.”
David Fairhurst- Environmental Performance Manager, Scottish Parliament

This report considers savings achieved for the CRAC units, subsequent savings on the AHU’s will be reported separately.

Challenges and Actions

Site Survey

An initial site survey was carried out on the HVAC equipment, with measurements taken of power consumption and performance. Based on the data collected, ebm-papst UK was able to design a suitable EC fan solution and produced estimates of energy savings and paybacks. The site survey looked at CRAC units, AHU’s and fan coil units, and based on the estimated energy savings it was decided that the initial trial was to be carried out on one of the Airedale CRAC units (DF50CW).

Trial Unit

The trial was carried out on an Airedale DF50CW down flow CRAC unit. Each computer room contains two air conditioning units, the majority of these being down-flow units, which are installed on a raised floor. The trial involved replacing the existing fan (AC belt driven blowers) with new EC backward curved RadiCal fans, and also relocating the fans into the floor void (*).

The relocation of the fans into the floor void involved opening up the floor of the unit, and lowering the backward curved fans into the space, the EC fan is mounted in a custom frame which allowed for easy installation.

Once installed, the EC fans were set to meet the same air flow as the original AC fans - this was done by use of a simple potentiometer that provides a 0-10v control signal to the EC fans. The current and power draw of the fans was then measured and compared with the original AC fans.

The trial resulted in a reduction in current draw of approximately 50%.

The original fans

Two off AC forward curved belt drive blowers, positioned inside the unit.

The new EC solution

Two off EC backward curved fans, positioned in the floor void. For down flow units, if the floor void is deep enough, installing the fans in the floor void can provide additional energy savings due to the reduced operating pressure.

Full installation. Following the trial on DF50CW, which resulted in a reduction in current draw of approximately 50%, it was decided to continue and upgrade the fans in all the computer rooms. A total of five computer rooms have now been upgraded with a single CRAC unit per room, however, each room has two CRAC units with one always on standby. The standby unit has not yet been changed to EC.

To achieve further energy savings ebm-papst UK has recommended that rather than have one unit on standby, a more efficient solution is to run both CRAC units at the 50% performance (to give an overall matched air flow). Due to fan flaws this will result in an additional 50% reduction in energy consumption for the same performance.

To satisfy the need for back-up in the event of one of the two units failing, the units will be linked via an upgraded Airedale control, which means that the EC fans of one unit will automatically ramp-up to compensate for any failure of the fans in the other unit.

Lessons & Results

Power measurements were taken on all units before and after the upgrade to EC fans. In all cases the air flow of the EC units was set to the same as the AC units.

Savings varied dependent on the size and number of fans per unit, the larger units which have two fans fitted showing more savings than the smaller units with only a single fan, however, the overall energy savings are still significant.

Measurements taken include: current draw, power draw and power factor.

The initial upgrade of one CRAC unit per computer room has resulted in energy savings of approximately 50%, with an annual reduction of 11.5 tonnes of carbon and a nancial saving in the region of £7,700 per year.

When the second phase of this upgrade has been completed and all CRAC units are running, rather than leaving half the units on standby, the estimated saving will be in the region of 20 tonnes of carbon and £13,500 per year.

It was also noted by the client that due to the higher efficiency of the EC fans, the motors run cooler and therefore the overall cooling load in the server rooms was reduced.

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Contacts

As world leaders in energy efficient fans and motors ebm-papst knows that the simplest way to reduce the energy consumption in buildings is to ensure that all heating, ventilation and air conditioning equipment is fitted with the highest efficiency EC fans. With HVAC equipment accounting for more than 40% of a commercial buildings energy consumption, making it more energy efficient can offer considerable energy and CO2 savings. ebmpapst.co.uk

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