One of the most energy-efficient private houses in the world was built in Hengelo (the Netherlands) in 2016, using state-of-the-art energy generation and conservation technologies.
The Lofthouse 2-story cottage with area of 240 m2 was created in the loft style and has completely self-contained energy consumption (Net Zero Energy). Created by BKVV Architekten architectural bureau, the house is focused on simplicity and functionality.
The cottage was built in just 7 weeks using fast construction technology. The house stands on a slab foundation with steel frame, while the building envelope is made of 100 mm thick Ruukki Energy sandwich panels with PIR core with Design Tokyo S18 design profiles cladding. Such a solution allowed to obtain better air-tightness and achieve more expressive building appearance. The soft sinusoid shape of the facades and roof provides effective color play with sky reflection , and the large panoramic windows give a fantastic view to the meadows.
In winter the sun serves as a passive source of heat through the windows with triple-pane glazing on the western and eastern facades. The thermal resistance of insulated hollow-section floor slabs R = 4.5 m2K/W, walls and roof – 6.39 m2K/W, and glazing – 1.24 m2K/W.
Due to such a high insulation degree and air tightness (Qv = 0.2 m3/h*m2), combined with modern technical equipment, the building became maximally energy-efficient and comfortable. The high air-tightness of the building envelope and the ventilation system with heat recovery (95% efficiency) allow to save energy resources and keep the optimal microclimate inside the premises. With building dimensions of 18х8 m and internal volume of 860 m3, heat losses at the temperature of -10°C comprise only 5 kW.
The cottage interior is implemented using visible building structures: steel frame, prefabricated reinforced concrete slabs and sandwich panels, creating a modern style. The visible surfaces of sandwich panels are stylishly matched with painted walls and glass structures.
The cottage has a heat pump installed for heating and hot water supply, operating according to the “water-water” principle. The main advantage of a heat pump is the possibility of passive cooling of the building in summer. The ” heat-insulated floor” system with frequent pipe location enables using a heat transfer agent with very low temperature. During the first heating season, the temperature of incoming transfer agent did not exceed 26°C, while in the premises the system managed to achieve the room temperature of at least 20°C. The reinforced concrete partition walls are used as heat accumulator, allowing to preserve heat for up to 24 hours, thus creating a possibility to heat premises during peak energy generation.
The shower water supply system for the envisages a heat exchanger, which pre-heats the supplied cold water from the shower drainage, thus allowing to save approximately 45% of hot water.
Electric power is generated by 20 photoelectric panels on the roof of the utility building, generating about 5 kWh.
With annual energy consumption of 4,912 kWh, the systems of the house generate 6,200 kWh, ensuring the surplus of 1,288 kWh. The energy surplus is stored in the accumulators for further useage in the household.
The water in the area of the construction is very hard, thus most residents use a water softening system. The design of the building envisages filtration of rainwater coming from the house and the utility building, collecting it into the 7,500 l tank. This is enough for approximately 5 weeks consumption. All water taps including the shower, toilet bowl and washing machine are connected to this tank, except for the kitchen potable water tank.
Due to the high sustainability indices, the Lofthouse cottage gained the title of the most sustainable house in the Netherlands in 2020 in the category of houses with area of over 175 m2.