With every building that has a basement car park the floor above will need to be insulated in some way from the conditioned spaces above. In a boarding house this is especially so, given the 24 hour operation and occupancy of the building. The windows also present a challenge for the energy design because the window area is maximised to provide as much natural light as possible but must also avoid as much heat loss as possible. This becomes a balance between cost, window size and energy efficiency.
This project is a 3 storey boarding house with a basement level car park. The standard Deemed to Satisfy (DTS) approach required three different glazing types on each of the East, West and South facades to achieve compliance with the minimum requirements of the Building Code. The DTS assessment required double glazing on the west façade, tinted windows on the east façade and clear windows on the south facade.
Using the verification method from the BCA (JV3), all the windows and doors were rationalised to one specification of tinted low-e glass in aluminium frames and the floor insulation above the car park was avoided and the roof insulation was increased from R2.5 to R3 batts. This solution provided an overall energy usage better than the Deemed to Satisfy building, and reduced the construction cost by $13,000.
The verification method (JV3) takes into account the estimated energy usage for the proposed new or modified building and compares it to the estimated energy usage of the Deemed to Satisfy requirements for the proposed building. This allows for a high level of flexibility in how the best energy outcome can be achieved. In this case additional roof insulation and low-e glazing all-round the building were used to compensate for the removal of the floor insulation above the car park and provide an overall cost saving.
The estimated annual energy demand of the JV3 solution was 289.4MWh which is less than the DTS solution and achieved an overall cost saving of $13,000.
