RAC brings you the latest VRF updates, including case studies and comments from key manufacturers on this most ubiquitous of AC technologies
“EN14825 has already happened for split systems in a drive to increase seasonal efficiency and reduce standby power, writes Mark Grayston.
Although it is delayed for VRF systems, the market is still calling for high seasonal efficiency of VRF and manufacturers are responding with changes to the way units are designed, so that seasonal efficiency is front of mind from the outset.
One of the key new features is automatic refrigerant temperature control, which we released last year. This varies the capacity delivered by varying the refrigerant temperature, which in turn reduces power input and improves comfort. This technology offers a level of control above and beyond that of a standard VRF system to increase efficiency. The added benefit is also an improved comfort level – the true requirement for the VRF system in the first place.
To improve the units still further, fundamental changes are required, such as the heat exchanger design. The current challenge that all manufacturers face is getting the required heat transfer at appropriate efficiency levels while minimising both the plant footprint and the refrigerant volume.
Integrated design of the system is vital for optimising heat recovery, so we are seeing more whole-building designs, which factor in hot water from VRF, link in air curtains etc, and consideration of occupancy patterns and solar gains.
Controls are important to tie all this together and the systems would not work or advance at all without them. These have sometimes been value-engineered out because the true value cannot be determined.
However, the EN15232 standard is now available to ascertain the impact of control strategies on heating and cooling systems. The true advances in VRF can now be not only controlled and the value of them be understood, but they can also be monitored and reported on – energy monitoring through the outdoor unit, with an AE200 or EB50 controller and also remotely accessed 24/7 anywhere in the world.”
Mark Grayston is product marketing executive for Mitsubishi Electric
Panasonic makes a good HVAC call for WDS
Panasonic was called upon by Woodhouse Environmental Services to provide equipment for call-centre giant WDS, with the retrofit of its busy offices with an energy-efficient heating, ventilating and air conditioning (HVAC) system, working against strict time and space constraints.
Panasonic’s ECOi VRF systems, coupled with large ducted and wall mounted indoor units, were specified by Woodhouse Environmental Services for a quick, simple and energy-efficient installation.
WDS negotiated with the building owners to redevelop one of three buildings at the Discovery Court Business Centre in Bournemouth.
With the brief to remove and replace the old, existing system with a high-performance, easy-to-install system, design-and-build contractor Woodhouse Environmental Services required a product that offered a large selection of different units to cater for the large building.
The complete system required would need to provide for the high density office, provide heating and cooling efficiency, introducing continuous fresh air and removing stale exhaust air, while at the same time ensure a comfortable work environment at ideal temperatures.
As the installation was to be undertaken while the building was still occupied, it was imperative for staff disruption levels to be kept to an absolute minimum.
Woodhouse Environmental Services initiated a fast-track installation programme between June and October 2013, splitting the renovation into three phases to cover each ‘zone’ of the building, satisfying a tight budget, and staying within the allocated time.
In the first phase, Panasonic’s integrated ECOi VRF and heat recovery ventilation systems were installed to replace the existing air cooled chilled water system operating on R22 along with a ducted fan coil system, which no longer provided the efficient and reliable service in this demanding application.
The ECOi 3-pipe VRF system offers high efficiency and performance, while its sophisticated design makes installation and maintenance much easier, according to Panasonic.
Woodhouse Environmental said that specifying these units made for an all-round easy-to-use system, while its clever, innovative integrated technology meant wasted energy was avoided and significant savings could be
made on the building’s annual energy bills. Additional extras included an energy monitoring touchscreen control with multi-zone temperature adjustment, which made this Panasonic system ideal.
As part of the second and third phases, Panasonic’s ducted indoor and wall-mounted units were also incorporated into the building refurbishment. These systems were integrated to provide fresh air input and stale air removal, together with meeting the required noise level criteria.
Daikin’s VRV update proving popular in Europe
Daikin claims its VRV is one of the most commonly-specified systems for commercial buildings in Europe, in fact about 40 per cent of the VRF systems installed in Europe are Daikin VRV systems.
Its latest VRV IV, launched earlier this year, was developed by Daikin Europe’s European Development Centre in Ostend, Belgium, and complies with the latest environmental legislation on energy-using products.
Furthermore, it features three major enhancements: Variable Refrigerant Temperature technology; Continuous Heating during defrost and the VRV configurator, for simplified commissioning and servicing.
The Variable Refrigerant Temperature technology enable VRV IV heat pumps to respond to heating or cooling requirements by continually monitoring the required capacity and weather conditions. This automatic adjustment means the system only uses the power required to meet the load, resulting in 28 per cent less energy being consumed and a drop in CO2 emissions of 28 per cent, compared with previous generations of VRV.
Another of VRV IV’s developments, Continuous Heating during defrost, allows VRV IV to maintain a comfortable indoor climate all year round, for the first time in the history of air-to-air heat pumps. Heat energy is stored in a claimed unique heat accumulation element inside the outdoor unit and this energy is used during the defrost cycle to avoid a drop in indoor temperatures.
According to Daikin, it also means 100 per cent of the heating capacity is available all of the time, as the pipework and indoor units do not act as evaporators and their temperature is maintained.
The last of VRV IV’s innovations is the VRV configurator. This enables the remote configuration of settings that can be used at multiple sites, so less time is required configuring outdoor units. Ongoing maintenance is easier too, thanks to a graphical interface that allows engineers to evaluate operational data and errors.
A new landmark building in the heart of Glasgow, St Vincent Plaza, is being equipped with an advanced Toshiba air conditioning system to deliver outstanding energy efficiency and comfort for occupants.
Designed to have a BREEAM rating of Excellent, the 10-storey iconic office development will be cooled and heated by a Toshiba 3-pipe SHRM-i VRF air conditioning system, with full heat recovery.
The Toshiba air conditioning is being installed by Castle Building Services of Hebburn, Tyne & Wear, as part of a £5m M&E contract. The installation comprises 21 high-efficiency Toshiba SHRM-i VRF systems, plus a twin-ducted system, providing simultaneous heating and cooling.
Excess heat generated in areas of the building subject to high solar gain or internal heat sources will be harnessed for use elsewhere, or be used as energy to power cooling via a sophisticated thermodynamic conversion system.
The project required a combination of long refrigerant pipe runs, high SEER and SCOP values, and exceptionally quiet indoor fan coil units. The Toshiba solution selected was able to deliver the performance criteria.
Some 316 ducted fan coil units are being installed, linked to 41 outdoor condensing modules, with the system connected into the building’s BMS using Toshiba’s recently developed Black Pear interface.
The Modbus-based interface gives the building supervisor access to each fan coil, plus access to overall system timing schedules and temperature and air speed settings, enabling continuous optimisation of energy efficiency and occupant comfort.
Castle Building Services used Toshiba Air Conditioning UK’s design and selection software, which takes into account system loading, pipe runs and design temperatures for summer and winter, to determine actual cooling and heating values for each of the building’s indoor units.
Allan Carr of Castle Building Services said: “It’s a great tool and helps in the development and validation of system designs. It shows how conditions can be precisely met with the equipment selected, and provides confirmation that the installed system will deliver as specified.”
St Vincent Plaza is due to be completed in Spring 2015.