Analysis On Economic Benefits Of Office Building Energy Saving Measures In Tianjin

The energy consumption of construction in our country has been over 27.5% of the total energy consumption, and the building energy consumption ratio will continue to rise along with the accelerating growth of the total construction. Structures and air conditioning system are the main aspects which affect building energy consumption. According to Tianjin Design Standard for Energy Efficiency of Public Buildings which will be published after a period time, this paper used eQUEST energy consumption simulation software to analyze the economic benefits of a series of energy saving measures, and this paper also did sensitivity analysis on these measures. These measures include:reducing the heat transfer coefficient of the exterior wall and roof, using energy-saving glass and window frame profiles, strengthening the outside window insulation structure, adding external blinds, using energy-saving glass curtain wall, improving units performance coefficient, using appropriate units operation strategy, using large temperature difference and small flow system, using variable frequency pumps and exhaust heat recovery units, and improve the efficiency of the pump and fan. This study shows that:When considering to reduce building energy consumption, the economic benefits should be taken into account at the same time. This condition should be avoided where just for pursuing low energy consumption and ignoring the initial investment. For the office building in this paper, whose outer wall and roof load accounted for nearly 40% of total loads of the envelope, the thickness of exterior wall rock wool insulation board which made the least whole life cycle costs should be 90?110 mm, and the thickness of roof extruded thermal insulation board should be 110?130 mm. To achieve the economic insulation thickness, compared with no insulation, the exterior wall and roof area can save 25.89kWh/m2 and 37.90kWh/m2.The energy saving potential of the double low-e insulating glass is larger. Compared with the double hollow glass, the window area outside of every square meter can save 29.63 kWh electricity. Compared with the ordinary single-layer glass, the window area outside of every square meter can save 58.86kWh electricity. It can be recycled in 2?3 years, which results in a very good application prospect. The number of the running units should be appropriate. In this paper, the cooling load is 295kW, so 3 units is the best, and should be distributed in accordance with the strategy:"two big with a small". Using variable frequency pump and exhaust heat recovery units can reduce the load when the units are running, which have good energy-saving efficiency. It can save nearly million kilowatt electricity every year. Ordinary water pump frequency converter can be recycled in 2?3 years, while the payback period of exhaust heat recovery units are no more than 4 years. The enhancing of the efficiency of water pump and fan can get good economic benefits in a certain range. In this paper, when the water pump energy consumption accounted for about 20% of energy consumption, the pump efficiency at 70% is advisable, and the fan efficiency at 70?80% is advisable.As far as the units operation strategy and the using of energy-saving glass are concerned, if investing the same proportion of money, they could earn more lucrative profits, compared with other energy conservation measures. Compared with the equipment operation strategy and the strengthening of the external windows thermal performance, the energy-saving potential of exterior wall, roof insulation and external sunshade is lower. But their payback periods of initial investment are not long, and they could reap better economic benefits in their life cycle.