Anticipating energy efficiency requirements

By anticipating future changes in carbon reduction legislation, engineers can design highly energy efficient buildings that are ahead of future regulations and deliver outstanding running cost savings. Martin Passingham, Product Manager, DX, at Daikin UK, looks at how technological advances have revolutionised VRV capabilities, enabling heat pump systems to deliver efficiencies way ahead of other technologies.

Since their introduction 30 years ago, VRV solutions have proven to be a highly energy efficient way to control a building’s climate systems. Like all good technologies, VRV’s development has not stood still, improving energy efficiencies all the time. Indeed, the very latest VRV system incorporates variable refrigerant temperature control, which automatically adapts the system to the individual building and climate requirements, for even greater efficiency.

However, until now there has been an assumption that VRV is only suitable for certain types of applications, such as small to medium sized office buildings. But these assumptions are simply no longer true.

Integrated systems

Perhaps because of VRV’s modularity, it is often perceived as ‘one step up’ from a split or multi-split system – and therefore most suitable for buildings of up to 3000sqm. But in reality, the latest VRV systems can be applied on a much greater scale, to create fully integrated systems for buildings up to three times that size.

VRV also provides greater flexibility to meet current and future client requirements, because the system can be designed, built and commissioned floor by floor. It can be introduced zone by zone and tailored to the needs of each building tenant throughout a phased refurbishment programme. Because each floor – even each room – can be individually controlled to maximise energy efficiency and prevent energy waste, VRV is ideal for buildings with multiple tenants, which may have vacant areas and variable periods of high and low usage.

In fact, a genuinely versatile VRV heat recovery system operating in balanced mode to manage climate control over an entire building can increase energy efficiency levels massively.

For example, a typical office building may require cooling down to 16ºC, heating up to 21ºC, with 200 litres of water storage being required for washrooms and 150 litres of water storage for kitchens. By recovering the heat from indoor units in cooling mode, a Co-efficient of Performance (COP) of 3.97 can be achieved. In milder conditions, when 75% of the indoor units are in cooling mode with 25% in heating mode, the efficiencies rise to COPs of 5.57. But when the system is fully balanced between heating and cooling, efficiencies can increase to as much as 10.07.

However, to achieve these market leading COPs, it’s vital to analyse right from the start a building’s multiple requirements, usage patterns and varying occupancy levels, in order to design an intelligent solution that optimises energy efficiency and heat recovery.

This may mean specifying the system so that it is capable of cooling one area of the building that is experiencing the highest heat gains and transferring that reclaimed heat to other areas of the building that require heating or hot water. By doing so, recovered heat can be diverted to heat water, or to additional applications such as over-door air curtains, saving up to 67% in running costs when compared with electrically heated models.

Smart controls

The integration of a VRV system with the latest intelligent control systems can again increase energy efficiency even more. For example, the latest innovations in intelligent controls are capable of allowing users to set system schedules on a weekly, monthly and annual basis. These can take into account holidays and seasonal variations in demand throughout the year, ensuring the system is being operated in the most energy efficient way.

Additionally, smart controls can also monitor energy consumption across a range of equipment, including air conditioning, to pinpoint areas of a building where the most energy savings can be made.

The savings don’t stop there either. According to the Franklin + Andrews, one of the world’s leading construction economists, running costs for VRV heat recovery systems are up to £6.25/sqm of gross floor area. This compares highly favourably with a 2 or 4 pipe fan coil system, which can cost as much as £8.75/sqm and £10.75/sqm of gross floor area respectively – a 40-72% increase on running costs compared with a VRV heat recovery system.

For example, Franklin + Andrews estimates that a 2 or 4 pipe fan coil system could take up around 7% of the overall lettable floor area of the building, while a comparable VRV building would take up between 3-5%. This means that VRV allows developers to maximise the rental space, by requiring 29% less plant space than a chiller system.

Improve on current practices

Of course, cost savings must be matched by savings in CO2 emissions too, as designers strive to meet ever tougher targets for emission reductions in the years ahead. A framework of continuous improvements has been set for Building Regulations resulting in all new buildings being required to deliver zero carbon emissions from the energy required for heating, cooling, hot water and lighting by 2019. These challenging targets will require considerable innovations to improve on current practices.

Additionally, many organisations and local authorities use BREEAM as a mandatory design standard to ensure that both new build and existing premises meet the exacting requirements for CO2 emission reductions.

Again, heat pump technology can assist building designers in meeting the requirements of BREEAM by delivering heat into a building in an energy efficient, controlled way. According to the criteria specified within BREEAM documentation, specific credits can be given for integrated services and building management systems. Further awards for innovation are also possible, depending on the system design.

To achieve the highest level of credits for integrated system design, Integrated Environmental Solutions (IES) offers a new Daikin Dynamic VRV Systems Sizing Tool within the IES Virtual Environment (IESVE). This new software tool enables architects and engineers to easily evaluate the best option to lower building energy use, by accurately simulating annual loads, power input and efficiencies delivered by such systems.

In addition to being able to help meet these standards, the latest VRV technology has been designed ahead of anticipated European seasonal efficiency legislation, which is already law for systems below 12kW and is expected to be introduced for larger systems soon.

This is important because existing nominal energy efficiency ratings (EER) have resulted in a significant gap between design and actual performance. To solve this anomaly, a more accurate rating method – seasonal efficiency (ESEER) – has been developed.

Because it measures energy efficiency across the whole operating spectrum, seasonal efficiency is a more accurate measurement of the real-life energy efficiency of systems and gives an indication of how efficient an air conditioning system is when operating over an entire cooling or heating season.

So the latest generation of VRV systems offer a highly versatile and flexible solution to meet today’s energy efficiency requirements, as well as anticipating many future changes.