Residential CO2 Heat Pump


One of today's examples is an Energy-efficient and renewable residential CO2 heat pump

About technology
An air to water heat pump is a very efficient device that uses heat in the ambient air for hot water production. Its heat energy output is about three to five times as high as the electricity input. The way it works is opposite to that of an air conditioning system: it uses a refrigerant cycle with a compressor and heat exchangers to extract heat from the ambient air and transfers this heat to water.

A CO2 Air to water heat pump is a good fit for:

  • High temperature domestic hot water production
  • Space heating for well-insulated homes (nearly-zero energy homes or passive houses)

About product
DENSO first introduced CO2 refrigerant to its Air to Water Heat Pumps in 2001, in Japan. Known as ‘Eco-Cute’, the product‘s improved energy efficiency meant that less domestic electricity was required.  As a result the innovation won six globally recognised energy and environment awards, including the 2002 EPA Environmental Climate Protection Award from the U.S. Environmental Protection Agency.

DENSO’s CO2 Air to Water Heat Pump was first introduced into Europe in 2009 and set a new standard for compact size, light weight and low noise. It is supplied as original equipment to heat pump manufacturers. DENSO CO2 Heat Pumps are now starting to be used in homes across Europe, supplying efficient, eco-friendly heating and hot water.

Typically heat pumps use a synthetic refrigerant gas such as R410A, which has a Global Warming Potential (GWP) of 1725.

DENSO and Stiebel Eltron team up for CO2 Heat Pump

Stiebel’s new LWZ 604 Air System features DENSO’s CO2 (R744) heat pumps and uses ventilated air to carry heat, lowering heating costs and emissions

Stiebel Eltron +DENSO Heating

In light of the EU Parliament’s target to allow only "near-zero energy houses" to be built by 2020, it is clear that the automotive industry is not the only sector coming under pressure to lower its emissions.  DENSO and Stiebel Eltron, a leading manufacturer of Heat Pumps, are paving the way for this greener future with the introduction of a new air-to-air heat distribution system for homes which uses their ventilation system to carry heat around the house, dispensing with traditional, less efficient water-based systems. The new system will go on sale to the construction industry in Germany in October 2017.

Ventilation Systems

In today’s well isolated new build homes, a controlled ventilation system is required to ensure the hygienic exchange of air from the outside to the inside of the house. Stiebel’s LWZ 604 Air System makes use of this ventilation system, giving it the dual purpose of distributing outside air throughout the building as well as carrying the heat emitted from DENSO’s heat pump. Using air as a heat carrier eliminates the need for a water-based heat distribution system, as the volume of air circulating the house is sufficient to hold enough heating for the entire building.

DENSO ‘Eco-Cute’ CO2 Heat Pumps

Integral to the system is DENSO’s CO2 Heat Pump which uses a refrigerant cycle with a compressor and heat exchanger to extract heat from the ambient air and transfer this heat to water at the start of the central heating process. Typically Heat Pumps use a synthetic refrigerant gas such as R410A, which has a Global Warming Potential (GWP) of 1725.  DENSO’s Air to Water Heat Pump was the first of its kind to use the natural refrigerant carbon dioxide – which has a GWP of just one. 

 The Heat Pump is highly efficient and the heat energy it produces is around three to five times as high as the electricity input. DENSO was the first company to bring CO2 Heat Pumps to Japan, and has installed over one million units to date. In light of new EU building efficiency and HFC refrigerant phase down targets, their role as an energy efficient way of space and water heaters will no doubt make them an attractive alternative to models with traditional refrigerants in Europe as well.

Cost saving

Stiebel Eltron highlights the cost-saving elements of the Air tot Air System both during construction as key selling point for the industry. Dr. Kai Schiefelbein, Managing Director of Stiebel Eltron said: ‘We give builders the opportunity to completely dispense with the water-based distribution system of conventional heating systems. The elimination of this system saves several thousand Euros in the planning and construction of new homes.’