A 10-class renovation: intervention on the envelope and transition from boiler to heat pump

Varese. Italia

2024

Aquarea Air to Water Heat Pump, Residential

Outdoor units: WHWDG09LE5
Indoor units: WHSDC0509L3E5

Designer: Eng. Alessandro Giuliani Technical Director of the Engineering Studio NRG Zero S.r.l. of Inarzo (VA)

Installer: Massimo Terni - Emmeti Impianti di Casale Litta (VA)


In the province of Varese, a three-storey building, consisting of three residential units, has been the subject of a very complex energy redevelopment project, aimed at drastically reducing consumption and optimising the systems, benefiting from tax breaks.

Challenge

Prior to the redevelopment, the two main building units were served by a Rotex heating and DHW system, which included a condensing boiler, a 500-litre storage tank and a solar thermal system. The third unit was equipped with a traditional gas boiler. The system was replaced, moving from a boiler to the implementation of a heat pump, with a significant impact from the point of view of the energy efficiency of the entire building.

Solutions & Tech Applied

In order to increase the energy efficiency of the building, it was decided to replace the two gas boilers with a centralized system consisting of two Aquarea L Series heat pumps with 9 kW R290 refrigerant capable of also managing domestic hot water. The heat pumps are supplemented by a 6.80 kW photovoltaic system with 9.6 kWh storage to optimize the exploitation of the available energy before it is fed back into the grid. 

THE DIFFICULTIES OF THE PROJECT

The redevelopment of the entire building required a major intervention, which presented some difficulties related to the continuity of energy services, which had to be guaranteed to the occupants, with the least possible disturbance during the period of the works.

"From a practical point of view, we first of all eliminated all the components of the existing plant in the two main apartments, temporarily using a backup boiler," says Ing. Giuliani, Technical Director of the Engineering Studio NRG Zero S.r.l. "Once everything was finished and the line to the third apartment was built, the installation of the external units was carried out and the system was progressively tested."

Massimo Terni, owner of the Emmeti Impianti Installation Company in Casale Litta (VA) says: "I really appreciate Panasonic products for the ease of installation, the silence in operation and the assistance that is constantly provided to us. I took the opportunity to work on a cascade plant using R290 gas with great interest; My first experience with this tecnologia.il system did not present any problems, although some additional attention was required due to the need to keep the energy services active and to coordinate with the work on the external coat. We had to manually eliminate the air in the circuit to avoid the remote possibility of gas infiltration into the circuit, in the event of a rupture of the exchanger".

WHY A CASCADE SOLUTION WITH NATURAL REFRIGERANT?

Ing. Alessandro Giuliani, for the project, chose a cascade system "because the coverage of the thermal loads and, above all, the production of domestic hot water for a multi-family building went beyond the power of a single unit. A further advantage derives from the better partialization capacity of the loads, which are very low at different times of the year. Our company uses Panasonic products with great satisfaction. The use of R290-powered heat pumps breaks down many of the traditional barriers that stood in the way of replacing existing generators with heat pumps, thanks to the high temperatures that can be reached and the high COPs (coefficients of performance) that characterize them. This technology stands out for its power and versatility, proving to be able to deal with critical issues related to the flow rates of existing systems and the need for domestic hot water production (DHW) and disinfection."

THE RESULTS OF THE PROJECT

Thanks to design choices focused on energy efficiency and the adoption of innovative and high-performance technological solutions, the building has made a leap of 10 energy classes, going from an initial energy class G (with CO2 emissions of 58.8 kg/m² year) to class A4. In other words, CO2 emissions have been reduced to 10 kg/m² per year, a value that, if we consider the energy produced by the photovoltaic system, can be virtually zero. The advantages obtained are many and tangible: reduction of energy consumption, lower environmental impact, increase in living comfort and, last but not least, an increase in the economic value of the entire property and individual housing units.

In terms of energy performance indices, the non-renewable performance index EPgl,nren increased from 310.39 kWh/m2 year to 36.80, while the renewable energy performance index kWh/m2 year EPgl,ren increased from 6.02 kWh/m2 year to 77.47 kWh/m2 year.

The two photovoltaic systems with a total of 6.8 kWp generate 7,294 kWh of electricity annually, exceeding the standard energy requirement of 5,928 kWh per year. 

The estimate of energy costs during the year for the building in relation to heating and domestic hot water is around 1,500 euros for the entire building.

For further information download the PDF: https://fcld.ly/jqryk9g

Capacity

9 kW

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