Meeting the demands of Lot 21

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Published: 18 June 2019


Martin Passingham, DX product manager for Daikin UK, explores the importance of Lot 21 in the industry and how VRV IV+ is leading the way towards meeting the new European Directive for Energy related Products (ErP) requirements by improving the seasonal efficiency.

Seasonal efficiency measures the true energy efficiency of heating and cooling systems during a period of one year. Unlike older heating and cooling methodologies, seasonal efficiency tracks a system’s daily operations to include temperature fluctuations and standby periods. After one year, the seasonal efficiency data gives a more in-depth, reliable and true overview of a system’s actual energy consumption. This is important because more than 95% of the environmental impact of HVAC systems comes from indirect emissions, which is the measured energy consumption of the unit. 
The European Directive on Ecodesign Requirements for ErP 2009/125/EC covers the indirect emissions (i.e. energy consumption) of a whole host of products. In relation to the systems that Daikin manufactures, Lot 21 of the ErP Directive is the category that considers air heating products, cooling products, high temperature process chillers and fan coil units for systems greater than 12kW when operating in cooling. 

Lot 21 uses a new measure of seasonal efficiency (referred to as Eta or ŋs, h and ŋs, c) which is the SCOP or SEER seasonal efficiency divided by the primary energy conversion factor (fixed as 2.5) minus the negative effect of controls on efficiency, which is 3%.

In heating: ŋs,h% = (SCOP/CC)-ŋF(i)
In cooling: ŋs,c% = (SEER/CC)- ŋF(i) 
SCOP: Seasonal co-efficient of performance
SEER; Seasonal Energy Efficiency ratio
CC: Primary energy conversion factor
∑Fi Sum of negative effect of controls on efficiency

From January, the minimum energy efficiency of air to air heat pumps is 133% ŋs,h% in heating and 181% ŋs,c% in cooling. These minimum requirements will increase again on 1 January 2021 to  a minimum of 137% ŋs,h%  in heating and 189% ŋs,c% in cooling. 

Luckily, Daikin has already taken great steps to ensure that VRV IV+ offers increased seasonal efficiency ratings, not just complying with the new Lot 21 legislation of the ErP regulations but exceeding them, thanks to brand new and improved compressor technology that delivers vastly improved seasonal efficiency in real world conditions, and which represents the next step in innovation within the VRV IV range since its launch in 2014.

Five years ago, Daikin’s pioneering revolutionary VRV IV system set a new standard in the industry, pioneering new levels of seasonal efficiency and comfort, which have since been introduced throughout the VRV IV heat pump, heat recovery, and water-cooled models. The launch of VRV IV+ heat pump once again sets a new benchmark for seasonal efficiency.

At the heart of the latest system, existing VRV IV features such as Variable Refrigerant Temperature (VRT) and continuous heating during defrost are matched by a completely redesigned compressor, which is fully optimised to ensure high performance at part loads - the main operation mode throughout the year. As a result VRV IV+ is already compliant with the new ENER LOT21 Tier 2 due to come into force in 2021.

New standard
Furthermore, the new compressor addresses a key issue that can occur during low load operation, which is that refrigerant leaks can occur from the high-pressure side to the low-pressure side in the compression chamber, resulting in loss of efficiency (Fig 1, below). In the new compressor, this has been resolved with the inclusion of a back-pressure control port that sends a small amount of high-pressure refrigerant from the compression chamber to the back of the scroll (Fig 2). This optimal separation of lower and higher-pressure sides within the compression chamber boosts seasonal efficiency to a new standard, delivering a 15% increase in efficiency.
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Fig 1
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Fig 2
VRV IV+ also uses a 4-sided heat exchanger with a new capillary design for optimised refrigerant distribution, providing the smoothest performance in any system loading.

As a result of all these innovations, VRV IV+ delivers 15% higher average seasonal energy efficiency ratio (SEER). With indoor ducts  the system SEER is as high as 38% higher with an 8HP unit and 41% higher SEER with indoor cassettes. In heating mode, VRV IV+ delivers 13% higher Seasonal coefficient of performance (SCOP) on average, or 16% higher SCOP for an 8 HP unit with indoor ducts. These developments in efficiency are what make the VRV IV+ a stand out system, through rigorous testing in true to life conditions, Daikin is proud to bring this developed technology to the market, exceeding the efficiency requirements of Lot 2.

So that designers can directly compare the efficiency of different systems, the ENER LOT21 free access website publishes data on different systems’ energy efficiency. This data is used to inform the technologies included on the ECA’s Energy Technology Product List, Building Regulations and wider technology benchmarking.  It is important for contractors and consultants to be able to benchmark the performance of both like for like systems and when comparing the efficiency of different types of technologies. So it is equally important that the data represents real life performance in a real system design within a building, rather than being modelled on a unit selection that will never be used in an actual application, in order to make the system appear as efficient as possible.

Environmental responsibilities
Not only have the tests been carried out in true to life conditions over the period of a year, to get the real picture of the capacity of the VRV IV+ but also, using the correct sized units for the conditions tested in, again to attain the most accurate and true ratings, to ensure absolute clarity for consultants and ultimately the end-user. 

It is important to us, as an organisation with a high regard for our environmental responsibilities, to know that the information we produce and promote to our customers is reliable and true. It has to be noted that, despite the need to comply with the Lot 21 legislation for HVAC products, there is no set requirement for the way tests are carried out and therefore some manufacturers may choose to provide unrealistic system selections in order to make their technology seem more efficient than it is in real life applications. However, Daikin is fundamentally opposed to this approach and instead chooses to conform to the spirit of the legislation and be transparent in every way.

With its next generation compressor technology that improves seasonal efficiency, the VRV IV+ is taking the next step in the journey towards lower GWP technologies and reduced carbon emissions. As the global leader in HVAC systems, Daikin is committed to upholding the principles of the Ecodesign Requirements for ErP by providing accurate energy efficiency ratings for its products that specifiers and end-users can trust will offer a genuine reflection of their performance in real life. ​​