A bank in Ludwigsburg, Germany, has seen its primary energy consumption reduced by 79.15% and its CO2 emissions reduced by 46% after installing an ammonia (R717) reversible water-source heat pump, according to Michael Eckert, Managing Director at HVAC&R contractor Kälte Eckert.
“Our customer gave a clear overview of the target: to curtail CO2 emissions, embrace natural refrigerants and reduce energy consumption,” said Eckert. “To meet the customer’s target, we proposed and designed a reversible ammonia heat pump with a total heating and cooling capacity of 252kW [71.65TR] and an electrical consumption rate of 65kW.”
Eckert shared details of the heat pump project at the ATMOsphere (ATMO) Europe Summit 2023, held last September in Brussels and organized by ATMOsphere, publisher of Ammonia21.com.
Eckert said that the bank, Kreissparkasse, was previously cooled by a liquid chiller using R134a as a refrigerant and heated via a condensing gas boiler. The liquid chiller was manufactured in 1998 and had begun to break down, motivating the bank to seek new cooling equipment.
“The refrigeration machine had a total capacity of 102kW [29TR] and initially had a COP of 2.55,” said Eckert. “Employing R134a as its refrigerant, with a GWP of 1,430, the system reflected the standards of its era but was inefficient compared to the latest technology available.”
“The adoption of the R717 heat pump reduced CO2 emissions by 46%, witnessing the shift from 73,250kg [161,488lbs] of CO2 emissions to 39,515kg [87,115lbs], which makes an immediate contribution to a more sustainable future,” Eckert added.
Eckert did not specify whether the reduction in emissions was due to the elimination of R134a leaks, the increased efficiency of the ammonia heat pump or a combination of the two factors.
The KSK Ludwigsburg building provides heating and cooling via a ventilation system, and according to Eckert, removing the piping for this system was not an option. Neither was removing the condensing gas boiler, which was manufactured by Viessman in 1994 and has a heating capacity of 170kW (48.2TR) and a capacity of 270 liters (71.32gal).
The boiler was retained to meet peak heating needs during the coldest months. Ludwigsburg is located just north of Stuttgart, and, according to data presented by Eckert, the average ambient temperature dips below 5°C (41°F) in January and February.
The new ammonia heat pump was installed in the basement and sends cool water to an air-handling unit in the attic. The temperature of its water source is between 6 and 12°C (42.8 and 53.6°F).
Eckert said the ammonia heat pump achieved a coefficient of performance (COP) of 3.88, making it more efficient than the R134a liquid chiller, which had a COP of 2.55.
“Our COP calculations delved into intricate considerations like outdoor temperature, enthalpy differences, requisite heating water, energy price structure and the CO2 emissions tied with electricity and gas sources,” said Eckert.
“[Using] this heat pump also significantly reduced operational costs by 27.45%,” he added. “This advantage proves the economic viability of our approach and makes a compelling case for the broader adoption of such sustainable technologies.”
The economic analysis encompassed energy prices, and at the time it was conducted by Kälte Eckert, electricity was priced at €0.2247 ($0.24) per kWh and gas at €0.08658 ($0.093) per kWh.
“Our calculations hinge on these prevailing rates, synergizing with our energy efficient system to substantiate the overarching economic advantages,” said Eckert.
“The total operating costs for the refrigeration machine and condensing boiler were €33,026.97 [$35,575.66] per year, whereas the new system can operate at €23,961.21 [$25,810.30] per year,” Eckert continued. “Hence, the results give a 27.45% reduction in operating costs.”
Eckert said he recognized the upfront cost of the system, which was not provided in his presentation, but said the cost would be amortized over a period of 13 years. His presentation also mentioned that the upfront cost was high due to the system being a “special plant construction,” and that if production scaled, prices would drop approximately 25%.
“This amortization period provides insight into the long term economic prudence of our sustainable retrofitting approach,” Eckert elaborated.
Eckert shared feedback from Karsten Geng, Head of Building Service for KSK Ludwigsburg, who said the new system will help the company meet the requirements set under Germany’s Building Energy Act (GEG), which mandates that buildings updating their heating systems use equipment powered by renewable energy.
“Our goal at KSK Ludwigsburg is to install modern technology in our already existing buildings,” said Geng. “With the new hybrid refrigeration machine and the condensing gas boiler, we can meet the requirements of the new GEG. This project is a new milestone for us and will be implemented in other KSK buildings.”
“Replacing this heat pump also significantly reduced operational costs by 27.45%. This advantage proves the economic viability of our approach and makes a compelling case for the broader adoption of such sustainable technologies.”Michael Eckert, Managing Director at HVAC&R contractor Kälte Eckert.