DENSO and Stiebel Eltron partner to help deliver the next generation of heating for low-energy, new build homes

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 ventilation systems 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 insulated, 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 heat 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 meaning the heat energy it produces is around three to five times as high as the electrical 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 energy efficient space and water heaters will no doubt make them an attractive alternative to models with traditional refrigerants across Europe.

Cost saving

Stiebel Eltron highlights the cost-saving elements of the Air to 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.’

Stiebel Eltron announced the air heating product at the BDF conference, a pre-fabricated house-builders conference, in April at Holzminden. Currently the system has been installed in a number of test homes, and will be available to the construction market in October.

Find out more

Further details of DENSO’s non-automotive product range are available online at