ZEB(Zero Energy Building) has become a rapidly evolving trend in the building industry across the world. ZEB is typically a grid connected building with extremely high energy performance. ZEB balances its primary energy use so that the primary energy feed-in to the grid or other energy network equals to the primary energy delivered to ZEB from energy networks.
Extensive research and institutional support towards the potential application of ZEB in the domestic market show that the country is riding on the wave of this new trend along with many others. In fact, dozens of demo ZEBs are presently built and being operated as part of pilot projects and “Zero Energy” based detached houses are now already moving towards commercialization in the private capital markets.
This article suggests the possible technical methodologies to save energy regarding the different type of buildings within the current stage of development, based on the case of domestic ZEB construction. Moreover, the article intends to go further by proposing the design approach method, especially elaborating on the role of RE energy and its effective application to the ZEB construction; the essential approach that’s required in completing the active method to control the residual load.
Generally 70-80% of the annual energy consumption in residential buildings is the thermal energy including heating, domestic hot water(DHW), cooking etc, and the only around 20% accounts for the electric energy. Accordingly, using the passive method that’s already familiar in the market such as super-insulation, super-window, air-tightness enables us to cut down on energy use in large scale. This provides reasons for residential ZEB taking the faster and easier way to commercialization, compared to non-residential ZEB. Thanks to the passive method, the highly reduced energy leaves relatively less amount of residual load for the RE(New & Renewable Energy) to cover, and the left load components are quite obvious. In the case of PV(Photovoltaics), one of the representative RE systems for detached houses, solar PV modules of 3kWp capacity are installed on the roof and have come into use, supplying most of the annual electric energy consumption in typical housing unit. Solar thermal system is mainly applied to meet the DHW load. For the ZEB housing with the highly cut heating load, it is rather inefficient to set up a separate system for heating and cooling. Recently, GCHP(ground coupled heat pump) system that provides both heating and cooling through one device is largely used. About residential buildings, the 3 RE systems above are creating the current mainstream market.
Whereas residential building is more focused on the consumption of thermal energy, it is electrical energy that takes up more than 70% of the total energy consumption in nonresidential buildings, lighting and the plug load in many offices for instance. With current technology, ways to reduce electrical energy consumption in buildings are very limited and its reduction effect is yet insignificant. Therefore, the introduction of high-level technology to produce electrical energy on building itself or on site becomes the prerequisite to actualize ZEB in non-residential areas.
The currently commercialized electricity generating systems that follow RE technology are photovoltaics, solar thermal power plants, bio pellet cogeneration system, fuel cells, and wind power. Regarding their reliability, safety, competence to match the demand and supply, installation conditions, and cost benefit etc, these systems are hardly applicable in the present stage. Nonetheless the integration of PV solar module to finishing materials of the building envelope, BIPV(Building Integrated PV), is receiving the most of the growing attention in this field of technology. In this respect, numerous enterprises from all around the world are now having their eye on PV and largely investing on them.