BREEAM for chillers
While BREEAM has an approach for awarding points for air conditioning using chiller plant, it does not take into account the use of free cooling in data centres — as Fin Farrelly explains.
BREEAM sets the standard for best practice in sustainable building design, construction and operation. The primary aim is to mitigate the life-cycle impacts of new buildings on the environment in a robust and cost-effective manner. BREEAM uses a scoring system to assess the environmental impact of new and existing buildings.
By recognising best practice, BREEAM encourages manufacturers like Airedale to improve system efficiency and resilience. The scheme most pertinent to Airedale is BREEAM’s New Construction scheme, in which commercial air-conditioning equipment can have a direct or indirect effect on achieving BREEAM points.
Section 12 Pol 01 (impact of refrigerants) focuses on the environmental impact of refrigerant, offering air-conditioning manufacturers a direct opportunity to score BREEAM points. For example one credit is available when the direct effect lifecycle (DELC) CO2 equivalent is less than 1000 kg/kW of cooling capacity. To calculate it, the following information is required.
1. The global warming potential of the refrigerant.
2. The total refrigerant charge in kilograms — such as 120 kg for a 500 kW chiller, spread over two circuits.
3. Cooling capacities .
4. Release factors as defined by BREEAM in Pol 01 calculator.
• Annual refrigerant leakage rate (% of refrigerant charge)
• Annual purge release factor (% of refrigerant charge)
• Annual service release factor (% of refrigerant charge)
• Probability factor for catastrophic system failure (%)
• Recovery efficiency (% of refrigerant charge):
Then apply the following equation:
(Refrigerant loss over lifecycle x GWP)/cooling capacity
— with the refrigerant loss in kg and the cooling capacity in kW.
Using this method, Airedale’s entire range of DeltaChill and DeltaChill FreeCool scroll chiller range up to 1MW would qualify for one BREEAM point. We are constantly developing our chiller technology to reduce the refrigerant charge or GWP in the system. One of the core objectives in our 1 MW scroll chiller range, was to increase capacity and achieve as high an efficiency level as possible, whilst minimising space claim utilising micro-channel coils. These have the added advantage of reducing refrigerant charge — a critical factor in the DELC calculation.
|Chillers that can provide mechanical and free cooling at the same time, such as Airedale’s DeltaChill FreeCool units, can save huge amounts of energy in data centres — but not qualify for a BREEAM credit.|
Affording Airedale’s 1 MW scroll chiller another credit is leak detection and automatic shutdown and pump down of refrigerant. All our latest products are fitted with refrigerant leak detection, which in most cases is located within the compressor enclosure. The sensor is positioned at the lowest point to ensure correct operation. A detection threshold of 100 ppm ensures excellent sensing of refrigerant leakage. The leak detector has relay outputs allowing for alarm monitoring via the Airedale controller. This relay output can provide facilities for refrigerant pump down and containment.
Where integrated into a building’s mix of services, it is possible for air conditioning to indirectly earn points in the following sections.
• Section 5, HEA03 thermal comfort. Cooling systems are significant contributory factors, dealing primarily with zonal cooling, control and integration of the system
• Section 6, ENE01 Reduction of CO2 emissions. Depending on application, cooling systems could represent a significant portion.
• Section 6, ENE04 low- and zero-carbon technologies. One credit within this section refers to free-cooling, but it only applies if the mandatory feasibility study has been carried out by an energy specialist and for certain free-cooling technologies.
The area in the new-construction scheme with most potential impact for chillers is specifically data centres. BREEAM has a designated assessment method and certification scheme that can be used at the design, construction, and refurbishment phases. The BREEAM goal is to provide assessment on the environmental impact of unoccupied or occupied data centre buildings. This is key to the UK meeting its own environmental targets, as data centres can account for up to 3% of total UK power consumption. BREEAM for data centres uses broadly the same framework, so chiller products would qualify under the same sections. The only additional credit would be available in data centres if their design was in accordance with the best practice for the EU code of conduct, including setting temperature set points to not less than 24°C, as measured at the inlet of the equipment in the rack.
Cooling as a percentage of total data centre power consumption typically ranges from 20 to 40%, meaning vast savings can be made by applying concurrent free-cooling technology. If the temperature set points for a data centre are set in accordance with current ASHRAE guidance up to 27°C, then, for example, a DeltaChill FreeCool chiller could typically offer partial free-cooling for up to 98% of the year (based on cumulative hours for London). This represents a significant energy saving and reduction in carbon footprint, yet would not qualify for a BREEAM credit as this would be issued under the above Section 6 ENE04, which does not take into account concurrent mechanical and free-cooling.
Fin Farrelly is marketing manager with Airedale International Air Conditioning.