The complex system for family houses meets the requirements of the new energy performance assessment of buildings

The ever-stricter requirements for the energy performance of buildings bring a number of new challenges that nearly all entities entering the process of constructing a new house face. An approach known as integrated building design is increasingly applied, placing significant emphasis not only on the technologies used but also on the structural and architectural aspects.

LWZ CS Premium

Requirements for technologies are increasing not only in terms of the efficiency and energy-saving behavior of technical devices but also concerning various system combinations and, consequently, their spatial demands. According to the Decree on the Energy Performance of Buildings 264/2020 Coll., the gradual tightening of requirements for "nearly zero-energy buildings" goes hand in hand. Since January 1, 2022, it has become extremely difficult to meet technological and construction requirements without the presence of various system combinations, such as heating through renewable energy sources, ventilation systems with heat recovery, photovoltaic systems, or other auxiliary systems. These technological units must be carefully considered already at the initial design stage of a quality building, while also ensuring the spatial efficiency of the technical facilities.

Fortunately, there is now a device that integrates all the required systems into one. LWZ CS Premium from Stiebel Eltron combines heating, hot water heating, cooling, and ventilation with heat recovery in one unit, additionally using renewable energy from outdoor air. The individual functional units of the device consist of a storage part with a hot water tank for washing with a volume of 235 liters and a functional module that includes a central ventilation unit with heat recovery with a maximum air performance of 300 m³/h and an air-to-water heat pump with an inverter compressor with smooth speed control and also with the possibility of reversible operation for cooling. The device also contains a circulation pump for the heating system, expansion vessels, an electric boiler, and, among other things, a full-fledged control system for the heating system of all its other components.

Placing the monoblock heat pump inside the house presents a fundamental advantage in the absence of any outdoor unit. The path of the utilized air begins with a rain-resistant facade shutter and continues through insulated air ducting to the heat pump heat exchanger, from where the air is expelled in the same manner through a second facade grille. The device is so quiet that it meets the required acoustic parameters at the boundary of the protected area of the neighboring building already at a distance of 1.6 meters from the outlet itself.

The grilles do not only transport air for heating, cooling, and hot water heating using the heat pump, but also for an independent central ventilation unit with a plate heat recovery exchanger, which can also be replaced by an enthalpic exchanger with moisture recovery if needed.

The uniqueness of the unit, therefore, lies not only in its compactness and the advantages of indoor placement but especially in the cooperation between ventilation and the heat pump. In a conventional ventilation unit, it is necessary to protect the heat recovery exchanger from freezing condensate by constantly preheating the incoming air at low outdoor temperatures, most often using an electric register with a power output in the range of several kilowatts.

A patented solution by Stiebel Eltron involves a separate branch of the refrigerant circuit of the heat pump, which is brought into the stream of fresh air drawn into the ventilation unit in the form of a small heat exchanger. Preheating is thus ensured by electric energy multiplied by the heating factor of the heat pump. The energy supplied in the air is not expelled from the device directly outdoors. Upon returning from the house and the heat recovery, the ventilated air at a temperature above 0 °C still has the potential to raise the average temperature at the evaporator of the heat pump. This air is sent precisely there and helps improve the performance and efficiency parameters of the heat source. The separate refrigerant branch can also be utilized in the summer for pre-cooling the air by up to 6°C.

LWZ CS Premium meets all the demands placed on modern equipment for new single-family homes. It is an energy-efficient and compact device that requires a footprint of 2×1.5 m; due to its very low noise level, it is also suitable for installation in dense urban areas. Its advantage is the ability to connect additional technological units such as increasingly used photovoltaic and solar thermal panels.