Large Air-to-Water Heat Pumps for Fuel-Boiler Substitution in Non-Retrofitted Multi-Family Buildings—Energy Performance, CO2 Savings, and Lessons Learned in Actual Conditions of Use

Abstract

The use of air source heat pumps (ASHP) in the specific context of existing multi-family buildings (MFB) represents an important challenge, especially in terms of performance and technical constraints in real conditions of use. This study concerns the actual performance of two non-retrofitted MFB (4047 and 7563 m2), whose original fossil heat supply was replaced by a centralized monovalent (2 × 156 kW) and hybrid (6 × 34 kW) ASHP system for space heating and domestic hot water. Based on a detailed monitoring campaign covering two years of operation, it can be concluded that both systems are able to supply the required temperature and cover the entire heat demand. By closely following up these pilot projects, constraints linked to integration and operation were identified. Optimization measures allowed us to increase the COP of the monovalent system (from 1.3 up to 3.4, with an optimized SPF of 2.3) and to raise the HP share of the hybrid system (from 50% to 67%, with an optimized SPF of 2.3). Both systems offer major progress in terms of CO2 savings (92% and 68%) and increased renewable energy share (75% and 43%), considering the hourly CO2 content of the Swiss electricity mix.

Renovation Results of Finnish Single-Family Renovation Subsidies: Oil Boiler Replacement with Heat Pumps

“…It is also stated in previous studies that the air source heat pump systems can reduce CO 2 emissions by up to 96% in the case of the Swiss electricity mixture [21]. Heat pumps installed in cold climate conditions usually have an auxiliary heating element to cover the peak heating load [21,22]. Abdel-Salam et al proved that the auxiliary heating element is not needed in the case of the ground-source heat pumps in Canadian cold climate conditions.…”

“…Ground-source heat pumps can achieve a higher performance coefficient than air-source heat pumps [20]. It is also stated in previous studies that the air source heat pump systems can reduce CO 2 emissions by up to 96% in the case of the Swiss electricity mixture [21]. Heat pumps installed in cold climate conditions usually have an auxiliary heating element to cover the peak heating load [21,22].…”

Energy Storage in Power to Heat or Cold Applications – an Analysis of Electrical versus Thermal Energy Storage

“…If also for domestic hot water, requiring higher temperatures for hot water storge, COP values are lower. An investigation of large air-to-water heat pumps for fuel-boiler substitution in multi-family buildings [36] resulted in COP's for space heating and domestic hot water being seasonally only 2.3. For industrial process heating COP values found range from about 5 to 6 for temperature lifts of 30 to 40 K [37].…”

Energy and Environmental Performance Comparison of Heat Pump Systems Working with Alternative Refrigerants

“…In this scenario, heat pumps represent one of the most efficient and promising technologies to reduce greenhouse gas (GHG) emissions linked to civil, industrial and commercial air-conditioning systems [3]. The adoption of HVAC (heating, ventilation and air-conditioning) systems based on electric heat pumps instead of traditional fossilfuel-based generators offers a series of important advantages, among which it is worth mentioning the integration with renewable-energy-generating systems (e.g., PV panels, solar collectors) [4,5], the simultaneous satisfaction of energy needs related to space heating/cooling and domestic hot water (DHW) production and, finally, the simple integration into pre-existing HVAC systems [6].…”