VRV with Thermal Storage

Description of the planned technology

What is VRV ?
VRV (variable refrigerant volume) system (trademark of Daikin) is a special heat pump system, practically a multi-split type of air conditioner, which use variable refrigerant flow control. It is also known as VRF (variable refrigerant flow) system (used by other producers). This technology circulates only the minimum amount of refrigerant needed at any one time and enables individual climate control of air conditioning zones.

VRVs are typically installed with an air conditioner inverter which adds a DC inverter to the compressor to support variable motor speed and thus variable refrigerant flow rather than simply perform on/off operation.
By operating at varying speeds, VRV units work only at the required rate allowing for substantial energy savings at load conditions. Heat recovery VRF technology allows individual indoor units to heat or cool as required, while the compressor load benefits from the internal heat recovery. Energy savings of up to 55% are predicted over comparable unitary equipment.

VRVs come in two system formats : two-pipe and three- pipe systems. In the case of two-pipe system all the zones must either be (all) in cooling or (all) in heating, while three-pipe system has the ability (with heat recovery) to simultaneously heat certain zones while cooling others.
VRV is a split system, where more indoor units can belong to one outdoor unit (in case of air/air system). In VRV systems the condensing unit may be air or water cooled. If water cooled, the condensing units are placed indoors and are much smaller and cooled with water by a closed type or circuit cooling tower or dry cooler.

The Hungarian pilot :
It is the renovation of a multifamily apartment building of 48 flats on 3 floors. Every flat consists of one room, one anteroom/kitchen and one bathroom, total size is ~22 m2. Currently, the flats are heated by individual gas burners (convectors), DHW (domestic hot water) produced by electric boilers individually. Energy efficiency is very low. There are no cooling equipments installed.

In the frame of SEEDs project – as a first step of complex renovation, a 3-pipes VRV system is designed to be established into 16 flats for heating and cooling purpose, and central DHW system will be built into 4 flats. The VRV system includes a hydro-box which heats the central DHW storage.
As part of further renovations, the VRV system (heating, cooling and central DHW supply) will be extended throughout the whole building.

The VRV system are designed to be integrated into a BEMS (building energy management system) and microgrid controller system for the optimization of power consumption, electricity production from PV and electric storage and EV charger. This control system is designed to interact with the local DSO (distribution system operator) platform to increase flexibility of the grid.

A specific technology / solution is designed to be developed to use the building’s thermal storage mass to influence the VRV’s electricity demand while taking into account the installed electricity storage, the electricity production of solar panels, and the car charging. Practically, the building mass will be used as a thermal storage.
In addition, the DHW storage could be extended to serve as a buffer thermal storage to be fit for participation in balancing of LV electricity grid, but only in case of significant consumption of DHW.

Status :
To our understanding, the Hungarian pilot – with the construction works and installation – is somewhat in delay. The site coordinator (ÉMI) is to manage and explain the situation; we have limited information on these issues, as – by our role – we were never part of these bilateral discussions and agreements.
As for “FAIRC” we have done everything that were required from us as inputs in due course and upon request; as we prepared and completed the design and the implementation plans, discussed and completed all inputs and specifications even for the relevant tendering documentation to help the procurement process etc.. Also, the required specification has been discussed and set out between “FAIRC” and Daikin Europe.

Upon request, our technical staff recommended three independent construction companies who submitted valid bids against specifications. Also, we comprehensively discussed all this in advance with the Site coordinator and later forwarded all materials for further use to them.