Green Building: Passive House or Zero Energy Building?
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The building sector is responsible for a large share of the world’s total energy consumption. It is estimated that built environment contributes around 30-40% of the worldwide energy usage and associated greenhouse gases emission (IEA 2012). “Green buildings” emerges to minimize the environmental damages caused by the construction and operation of buildings; Passive House and Zero Energy Building are two of them. This essay aims to give a brief introduction of Passive House and Zero Energy Building; and to compare their feasibility in Hong Kong.
Passive House and Zero Energy Building are “Green Houses” designed for minimizing the environmental impact of buildings; they achieve the goal in different ways. Passive House is a building, for which thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to fulfill sufficient indoor air quality conditions (Feist 2006). With-out active heating and cooling systems such as thermal windows, heat recovery are used such that indoor temperature can be automatically adjusted and thereby reduces the energy consumption of building by 70-90%. (UNEP 2007, iPHA 2010)
Figure 1 Operation of Passive House (Gröndahl, Gates 2010)
Zero Energy Building is a building with greatly reduced energy needs through efficiency gains such that the balance of energy needs can be supplied with renewable technologies (NREL 2006). Energy- efficient technologies and renewable energy systems are installed and energy produced is stored on site (UNEP 2007) so that the operation of building can rely on its self-produced energy.
Figure 2 Operation of Zero Energy Building (LaMonica 2009)
To assess the feasibility of Passive House and Zero Energy Building to be promoted in Hong Kong, the following are the requirements for comparison: (1) efficiency in energy conservation; (2) adaption to local climate.
In terms of the efficiency in energy conservation, Zero Energy Building
performs better. A Passive House uses no more than 15kWh per year and square meter of living space (iPHA 2010); while a Zero Energy Building achieves net energy consumption of zero and produces excess electric energy ofover 1700 kWh( Rosta, Hurt, Boehm, Hale 2008). Apparently, Zero Energy Building preforms better in conserving energy due to its ability of generating energy on its own, therefore it is more practical to promote Zero Energy Building in Hong Kong.
Page 2 Green Building: Passive House or Zero Energy Building? Essay
For adaption to local climate, Zero Energy Building isalso a more suitable choice for Hong Kong. Passive House’s emphasis on maintaining thermal comfort (iPHA 2010) may not be necessarily suitable for Hong Kong since Hong Kong has an annual range of temperature of 4°C only. (Hong Kong Observatory 2012) While Zero Energy Building allows different micro-generation technologies to be applied according to local environment; renewable energy system like solar panel (UNEP 2007) is suitable for buildings in Hong Kong due to the abundant sunlight there. In short, since Zero Energy Building can adapt to Hong Kong climate better, it is more feasible to be promoted in Hong Kong.See More on Energy