Models of efficiency

How will equipment with high energy-efficiency ratings perform in practice. The answer can come from dynamic simulation modelling based on good-quality real-life performance data. Richard Green of Daikin Airconditioning UK explains.

Balancing building services to provide comfort and ease of use while complying with legislation for planning is not an easy task. Increasingly, dynamic simulation modelling (DSM) is being used to determine the suitability of HVAC systems in buildings to quantify compliance with Part L of the Building Regulations while being able to observe the effects of these systems on the comfort of the occupants.

It is fair to say that the results of these simulations drive the energy and environmental design of most buildings. Modelling can produce an accurate and realistic simulation of the performance of climate control systems so that the true effects of design and performance can be simulated and understood.

But as with all software, the results that come out of DSM depend on the quality of the information that is put in. Manufacturers need to strive to give honest, transparent and proven information about their systems so that accurate assessments can be made.

This is why Daikin UK formed a partnership with Integrated Environmental Solutions to produce an accurate and realistic simulation of the performance of Daikin VRV systems, so that the true effects of design and performance can be simulated and understood. The specification tool is available as a plug-in to IES Virtual Environment 2012 (see below).

Field trials were carried out to measure real-life performance of the Daikin VRV system. The data, along with accurate publicly available data, was fed back into the IES Virtual Environment. It is important to note that the output of any specification plug-in tool should be based, as this one is, upon the thermo-mechanical operation of the system — including realistic performance increases from the heat-recovery effect and losses.

Full thermal dynamic simulations produce annual loads, power input and efficiencies, which can then be used to demonstrate system efficiencies in compliance with Building Regulations. This increased simulation accuracy often reveals that climate-control systems are far more efficient in operation than predicted by the seasonal energy efficiency ratio (SEER) method.

The data can then be used to assess alternative system configurations to give designers more flexibility and enable them to tailor a system to a building’s needs, while meeting the requirements for Part L of the Building Regulations and ever-tightening European legislation on energy efficiencies, such as the Energy Related Products Directive affecting air-conditioning systems under 12 kW from 1 January 2013.

It is therefore crucial that building engineers, software developers and manufacturers continue to work together to develop and improve specification tools for climate-control systems that can be integrated into modelling software. This will help ensure that predicted and legislated levels of energy efficiency and comfort are met, costs are controlled, and the best performance from the equipment is achieved.

The Daikin UK VRV specification tool is available as a plug-in to the IES Virtual Environment 2012 (IESVE 2012). The tool allows engineers to take the climate-control system-efficiency calculations from the IES system and calculate the best configuration for heat-pump and heat-recovery VRV systems.

Users also benefit from automatic sizing of the VRV system and selection of the correct indoor and outdoor units based on the building’s heating and cooling loads.

The plug-in, alongside the Virtual Environment, can simulate the building as a whole (including the VRV systems) and show realistically via simulation how these systems will perform — including defining setpoint changes, indoor- and ambient-air temperatures, and control strategy — taking into account VRV system attributes such as defrost, oil return and pipe-length corrections.

Dr Craig Wheatley, director at IES, explains: ‘Enabling customers to get this kind of detailed manufacturer’s data within the Virtual Environment has been a big driver, especially as technologies become more integrated. By partnering with Daikin we’ve been able to do the hard work for customers, which will help them understand and use such innovative solutions to the full.’

The software covers the entire Daikin VRV range, including all 2-pipe and 3-pipe options. It can make hundreds of thousands of individual calculations during analysis and be used throughout projects — from concept, schematic and detailed design, through to commissioning and operation.

The plug-in is free. However, training is required to ensure the best VRV system is chosen and installed correctly. Daikin will be holding a number of seminars around the UK at its regional branches in Birmingham, Bristol, Glasgow, Manchester and Woking.

The partnership between IES and Daikin UK to create this plug-in is just one example of the bespoke manufacturing capabilities IES is now offering as part of its Sustainability Hub.

Richard Green is engineering specialist for Daikin Airconditioning UK.

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