Xingfubao (happiness castle) is the name of the first certified passive house in China’s extreme cold climate zone in Urumqi, der capital of China’s Northwestern province of Xinjiang. The extreme climate of central Asia poses a challenge with temperature in the summer of up to 40°C and in the winter down to -30°C. The Chinese partners, the investor Dacheng Industrial Co. and the City of Urumqi construction Committee decided after careful study and visits of many energy efficient buildings in Germany to realize an ambitious goal: a modern building as the first passive house with a heat demand of 19 kWh per m2 and year which is just 13% of the required heat demand for new buildings in Urumqi. In cooperation with the passive house institute Darmstadt (PHI), a concept for a comfortable building was developed with mixed-use by restaurants, cafés, shops, offices and apartments. Because the building should show that sustainability can also be economically viable, many small measures needed to be combined.
The long-term project cooperation of German experts with local partners was facilitated by the coordination and research work by ifeu. It was sponsored by the German Federal Ministry of Education and Research (BMBF) as part of the Future Megacities research programme.
A first design draft was developed by Culturebridge Architects Grünstadt together with ifeu in collaboration with PHI and the Xinjiang Architectural Design Institute. The design phase focused on optimizing the A/V ratio, minimizing thermal bridges and maximizing internal and external heat gains. Energy balancing was performed by using the Passive House Planning Package (PHPP) developed by PHI; it allows detailed modelling including the contribution of internal heat sources.
The insulation of the exterior hull meets stringent requirements (u-values [W/(m2*K)] walls: 0.15, roof: 0.13, floor: 0.11 and windows: 0.8). For the first time in China, the German window company Rehau produced passive house windows with PVC frames. In order to maximize the solar heat gains in the winter, European producer Saint-Gobain manufactured glass in China that met the required g-value of > 0.5. For the ventilation unit with heat recovery an efficient model with energy recovery rate η >0.75 was provided by the US-based Conserv.
Air tightness of the building was achieved in installation of windows and doors: the first blower door test at a pressure of 50 Pa showed the success: the measured value of 0.2 h-1 was far below the required one of 0.6 h-1. Solar collectors on the roof reduce the need of natural gas as primary energy source and further improve the CO2 balance of the building. The colorful metal façade demonstrates that a sustainable building can be designed in an attractive way. A part of the building cost of 34 million CNY (4.2 million EUR) was covered by a grant from the City of Urumqi in the amount of 2.5 Mio. CNY (300,000 EUR).
The cooperation between the partners includes a wide array of activities: passive house study tours in Germany during the beginning phase of the planning, development of course materials to adapt the passive house design to the specific climatic conditions, capacity building for architects and planners in passive house design, and training of contributing companies in the state-of-the art installation of insulation materials and windows. It further required practical training modules for the combined installation of windows, insulation and façade components in shell construction, training for the correct installation and operation of a ventilation system with heat recovery, and the monitoring and quality control of the entire construction process.
It was decisive for the success of the project that German and Chinese partners developed trust during the many years in the exchange of experience in passive house design and realization. Interaction between the Urumqi City government and the investor, as well as the increasing collaboration during the construction phase involved training and capacity building for planners, technicians, and construction personnel. Because this was the first object built in Urumqi to the ambitious passive house standard, a large number of practical and logistical problems had to be resolved, from the adaptation of changes in intended use to the market availability of components such as windows and insulation materials. The proof for success can be seen in the fact that the observed heat consumption in the winter 2014/2015 was in good agreement with the calculated value.