Cases | BUILDUP

Abstract | The building provides offices for the General Secretariat of Information Systems (GSIS), a public administration agency belonging to the Greek Ministry of Economy and Finance. The building was initially constructed in the 1960. An initial retrofit took place in 2000. This was followed by a further retrofit in 2006 with the aim of improving the indoor environment and minimising building energy consumption.The following modifications were made during the 2006 retrofit. Shading systems were fitted on the south and west facades of the building to control solar gain both in winter and summer. Double glazing of the north façade was replaced with low emissivity double glazing in order to minimise the thermal losses through the building envelope and to improve thermal comfort in the adjacent office spaces. The HVAC system was upgraded and a new Building Management System (BMS) installed which controlled heating, cooling and a new demand control ventilation system supplying high density office areas (Figure 2). The BMS also records environmental conditions (internal temperatures, relative humidity, lighting levels) and energy consumed for heating and cooling. Energy consumption for lighting was reduced by replacing existing standard luminaires with energy-efficient fluorescent lamps (Osram Lumilux T5 HE) with a luminous efficacy of 104 lm/W. In addition, 26 m² of photovoltaic panels were installed to supply auxiliary systems and lighting on the 3rd and 4th floors.

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Web URL(s) of the case | http://www.buildingadvent.com

Lessons learnt | Although the retrofit provided significant energy savings for heating, cooling and ventilation, the post-occupancy comfort survey showed that there is still dissatisfaction regarding the thermal comfort in the densely occupied areas. Further changes could be made to the ventilation system to increase the ventilation rates in each office space. However, this would imply the replacement of the existing system with a new one, a solution much more expensive than the interventions already implemented. However, the demand control ventilation, based on CO2 concentration, in conjunction with the use of ceiling fans, provided an excellent solution for maintaining indoor air quality in the densely occupied offices at acceptable levels while at the same time achieving significant energy savings. The BMS also performed well in recording the building energy consumption and detecting any malfunction of the installed systems.

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