Research

Low-energy mechanical ventilation : a case study of two new office buildings

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Abstract

In 2010 an internationally renowned company initiated an architectural competition for two new office buildings to be constructed in Denmark. The design objectives were to construct a sustainable office building according to Danish low energy class 2015, with a good indoor climate and with as little energy consumption as 41.1 kWh/m2/year including heating and all building services with no use of renewable energy such as PVcells or solar heating. One of the key means of reaching the objectives was to implement mechanical ventilation with low pressure loss and therefore low energy consumption. The project consists of two buildings, building one is 6 stories high, and building two is 4 stories high. The buildings have a gross area of 50,500 m2 including underground parking. The ventilation and indoor climate concept was to use mechanical ventilation together with mechanical cooling and fanassisted natural ventilation for free night cooling, hence minimizing the energy consumption for cooling. The paper describes the initial ventilation requirements and the implemented ventilation system. The specific fan power, SFP, with maximum air flow rate was measured to be 0.9 kJ/m3 to 1.2 kJ/m3, with an average of 1.1 kJ/m3. The yearly mean SFP based on estimated runtime is approx. 0.8 kJ/m3. The case shows the unlocked potential that lies within mechanical ventilation for nearzero energy consuming buildings.