Energy savings of 53% were measured for this energy efficient office retrofit project funded by DANIDA for an existing government office in Jakarta, Indonesia. IEN Consultants were engaged as the energy design consultants and did - in collaboration with the local consultants - come up with following energy efficient retrofit strategies:

1) Air-tight building envelope
An innovative "double-glazing retrofit" of the existing leaky single-glazed window frames through which both street noise and hot humid outdoor air entered the offices. The retrofit solution was to add a clear glass single glazing on the inside (resting on the window sill) and to leave the existing glazing in place. This dramatically improved the air-tightness and significantly reduced the street noise entry. Air-tightness was also improved above the suspended ceiling, where it was found that no effective barrier was in place apart from the external facade cladding. Likewise, air-tight doors and automatic door closers were used for spaces facing the naturally ventilated staircase / corridor.

2) Daylighting
The existing office has permanently closed vertical blinds. These were replaced with perforated horizontal venetian blinds and combined with a mirror reflective lightshelf placed at the external window sill. The lightshelf was slightly tilted outwards (about 5-10 degrees from horizontal), so that the top of the lightshelf would not be visible when seated, and hence would not be a source of glare. The facade was facing North and had a overhang, so only diffuse light at lower angles would be reflected into the building. The reflected light would travel parallel with the venetian blinds, hence, allowing the daylight to enter virtually unhindered.

3) Demand Ventilation
CO2 sensors were installed to regulate the outdoor air supply in accordance with the occupancy, hence, saving energy for dehumidification and cooling of excessive outdoor air supply

4) Energy Efficient Cooling System
A VRF system (Daikin) was installed to cater for all the cooling needs, hence, replacing the low-efficiency old centralized cooling system.

5) Energy Efficient Lighting
The T8 lighting was replaced by energy efficient LED lighting with daylight and occupant sensors, such that the lights would only be on as and when needed.

6) Energy Management
Sub-meters were installed for provide a breakdown of the energy consumption as well as continuous monitoring for easy energy management. An energy management display screen was installed for visitors to see.