The Lexus Centre in Melbourne has undergone a number of transformations to become the state-of-the-art sports stadium. Originally designed as a competition swimming venue, the centre is the last major structure remaining from the 1956 Olympic Games.
According to owner/operator, Melbourne & Olympic Parks Trust (MOPT), the building’s latest refit was undertaken to address heat load issues within the facility’s auditorium. After conducting an in depth cost-benefit analysis of four possible options, MOPT decided that replacing the glass in existing windows with double glazed units would provide the comprehensive solution.
Refurbished and extended in 2002 to meet the needs of the new tenants, only the administration areas were fitted with refrigerated air-conditioning. The large auditorium space shared by the two organisations for athlete training was left uncooled, due to the high costs involved.
However, after the 2002 refurbishment, every one realised that extreme summer temperatures were increasing the temperature inside the building also. The gymnasium and training area were used frequently throughout summer. Feedback by the tenants regarding extreme summer temperatures in the main sporting area was supported by temperature data recorded over the summer of 2006 to 2007.
When considering how to reduce heat in the space, several elements were taken into account, including: the initial cost, estimated maintenance costs over ten years, the expected heat and the risk involved. With the building heritage listed due to its historical significance, options such as external shading louvres or awnings were unlikely to be approved under the Heritage Act 1995, which aims to retain the building’s exterior in its original appearance.
Along with double glazing, other options to undergo a cost-benefit analysis were: installation of internal blinds, air-conditioning and tinting of the existing glass. Internal blinds were affordable but projected maintenance costs were high.
Providing a 95% reduction in heat over the existing conditions, a fully air-conditioned training area would offer a complete solution but at a relatively high cost. Tinting the existing glass was favourable but as the existing glass was not designed to have a film applied, thermal cracking was a possibility.
Using double glazing to reduce heat in the auditorium was suggested by MOPT Building Services Manager, Roschel Vaz. Roschel understood that double glazing would be effective than a tint film.
Several quotations were evaluated and ViewTech Glass was awarded the contract. ViewTech Glass outlined several options. In conjunction with glass manufacturers, Viridian provided a number of different glass combinations for MOPT to consider. The final double glazing choice comprises 6mm VFloat Grey (toughened) and 6mm EnergyTech Low E (toughened) with a 12mm air spacer.
Double glazing appeared to be an expensive option, but long term calculations showed that it to be in line with or less expensive than the other options. This double glazing configuration was estimated to reduce heat gain from solar radiation by 50% relative to the previously installed clear single glazing. Further to its ability to reduce solar heat gain, the double glazing also reduces heat conduction through the façade by 50%. With this significant reduction in heat gain, it is possible to maintain internal temperatures below or near external air temperatures while the sun is out and until the cool evening change sets in. This is achieved by utilising the thermal mass of the concrete base structure and by means of passive ventilation when external air temperatures are below the internal air temperature.
The tint featured in the double glazed units is through the glass, resulting in a less reflective or mirror-like look. This glazing was approved by Heritage Victoria.