Solar hybrid air-conditioning design for buildings in hot and humid climates - Solar Energy Sciences and Engineering Applications - page 485

Solar hybrid air-conditioning design for
buildings in hot and humid climates
Kwong-Fai Fong
Division of Building Science and Technology, College of Science and Engineering,
City University of Hong Kong, Hong Kong, China
15.1 INTRODUCTION
In hot and humid cities, space conditioning and refrigeration generally consume close
to half of energy use in office and residential buildings. In conventional air-conditioning
provision, electricity-driven equipment is commonly applied. The projection of energy
supply finds that fossil fuels may still play a very significant role in 2035 if there is
no abrupt change of energy use (IEA, 2010). The Intergovernmental Panel on Climate
Change (IPCC) has recently issued a special report about the role of renewable energy
sources in climate change mitigation (IPCC, 2011). It indicates renewable energy,
including solar energy, has a large potential to mitigate greenhouse gas emissions.
But how can renewable energy be widely used in the building sector?
In 1977, the International Energy Agency (IEA) set up the Solar Heating and
Cooling Programme to promote the technology development and standardization of
solar heating and cooling since (IEA, 2012). In recent decades, solar air-conditioning
has been broadly advocated (Altener, 2002; Eicker, 2009), aiming mainly at small
and medium applications in buildings. Although solar air-conditioning has been pro-
moted, most of the demonstration projects are found in temperate and cold climate
regions where the emphasis is placed on heating rather than cooling. The demand for
cooling systems is not a priority and the holistic system design for both cooling and
dehumidification is seldom touched.
In fact, the market for solar-thermal collectors is growing rapidly around the
world. Mainland China has the largest total capacity of evacuated tube and flat-plate
collectors in operation, accounting for almost 60% of the world market (IEA, 2011).
The capital cost of solar-thermal collectors has been reduced by about 20% for each
doubling of installed capacity (IEA, 2007). Therefore, the application potential of
solar-thermal energy becomes economically and technically viable from such blooming
production. With continuous population and economic growth, the strategic design
of solar air-conditioning should secure the increasing energy demand and attain low
carbon urbanization in the long run.
General design guidelines and demonstration projects have been established to pro-
mote wider use of solar air-conditioning (Delorme et al., 2004; Wang et al., 2009). In
addition, basic design calculations and discussions have been provided for various com-
mon solar refrigeration and air-conditioning systems (Eicker, 2003; Henning, 2004).
In recent years, solar energy systems have been designed in building systems through
solar heating and cooling, as well as different integrated methods (Wang and Zhai,