28 Energy Efficient Air Conditioning Measuring energy efficiently
The future of a sustainable built environment depends heavily on how building owners and managers improve the energy efficiency of new and existing buildings. Here, Daikin UK product manager, Martin Passingham, assesses various types of measurement and how air conditioning equipment in particular is specified to meet energy reduction targets.
L
AST YEAR SAW a number of changes to legislation, codes of practice and standards covering the energy efficiency of buildings, with the new Part L in April; updating of the non- domestic Renewable Heat Incentive in May and an 33% increase in the cost of carbon allowances under CRC Energy Efficiency Scheme for 2014-15.
Government has now set its sights firmly on tackling the carbon dioxide emissions of non-domestic buildings to help it meet its commitments under the Climate Change
Act 2008: to reduce CO2 emissions by at least 80% of 1990 levels by 2050. Pressure is also being applied by Europe. From 2019, all new non-domestic buildings in England will have to be built to zero carbon standards, as part of the Government’s commitments under the EU’s Energy Performance of Buildings Directive (EPBD). Additionally, the EPBD will also require new non-domestic buildings to be issued with an energy performance certificate.
Part L of the Building Regulations, which already sets limits on the emissions of new buildings, is expected to be the regulatory vehicle for achieving these zero carbon standards. Part L already requires energy efficiency standards of new non-domestic buildings to improve by 9% on the 2010 regulations. The rules also apply when specific building services work, including climate control, is carried out. With all of this in mind, building owners and managers need to ensure they understand the future energy demands of their buildings, along with changes to the legislative landscape, before specifying and procuring air conditioning systems. Similarly, contractors need to ensure they understand these drivers and the measurements behind them to ensure that the right equipment is used to help buildings to achieve these targets.
BREEAM and beyond
When designing new buildings or undertaking refurbishment work, many organisations use BREEAM as a mandatory standard to ensure that they meet the
exacting requirements for CO2 emission reductions. It uses approved techniques of measurement to assess energy efficiency, which covers everything from design and development to the building’s whole lifecycle.
ACR News February 2015
A typical BREEAM assessment will look at a range of factors including, but not limited to, the management of a building, best practice commissioning, water usage, the lifecycle of the construction materials used, surface water run-off and the effect of the building on the ecology around a site. Credits are accumulated throughout the build, or refurbishment of a building, to give a final BREEAM rating. The most credits are awarded for good energy management including the specification of climate control systems, so it makes good financial sense for building owners to invest primarily in air conditioning before looking at lesser- weighted options.
If BREEAM is the first consideration for building managers looking to meet energy targets, the next is the Energy Efficiency Ratio (EER). EER is a measurement used to describe the heating and cooling efficiency of air conditioners. It is measured by assessing the ratio of heating or cooling provided by a unit relative to the amount of electrical input required to generate it.
Thus, if an air conditioner generates 5kW of cooling from a 1kW electrical input, its EER is said to be 5.0. Therefore, the higher the EER, the more energy efficient the equipment is. Much like EER, Seasonal Energy Efficiency Ratings (SEER) is a way of measuring the true energy efficiency of heating and cooling technology, but over an entire cooling or heating season. SEER takes into account a number of factors, which together provide a much more realistic view of energy efficiency in real life conditions.
The performance of the equipment is now measured across different climate zones, at both partial and full capacity, in both auxiliary and stand-by modes and over different load requirements across the seasons.
The higher the
rating, the better – and most importantly, it’s a realistic measurement that brings us one step nearer to closing the performance gap.
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For building owners, the higher SEER rating is resulting in significant savings: not only from lower energy usage but also from the resulting product development. Innovations such as variable refrigerant temperature have led to increases in energy saving of up to 32%; with newer systems offering the flexibility to achieve top efficiency throughout the year, balanced with a quick reaction speed on the hottest day or at peak loads.
Specification
However, sizing plant correctly to enable building managers and users get the most out of their climate control system is absolutely crucial, as even with the right SEER calculations, incorrectly sized equipment can be detrimental to a building’s energy targets. More often than not, building use, the size of the building serviced and its occupant levels will point towards the required plant size. Only accurate specification can ensure that the system strikes a balance between performance and cost. Under-specification can lead to a mismatch in required and actual cooling/heating outputs, while over-specified plant may result in increased operating cost and prevent the climate control system from achieving its maximum efficiency.
To achieve this, manufacturers and distributors such as Daikin UK offer dynamic VRV systems sizing software. This software is fully integrated with IES Virtual Environment (IESVE 2012) to deliver advanced modelling capability for heat recovery VRV systems.
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