We know that working in this industry means having to keep abreast of the constantly changing face of building regulations, with few areas having received more scrutiny than energy efficient performance requirements.
Window assemblies along with external shading and heating ventilation and air conditioning (HVAC) designs used in commercial projects are being reshaped to comply with ever more stringent performance requirements set by the BCA, NABERS and the Green Building Council.
There is little wonder this is occurring, as HVAC units are the largest single user of energy (accounting for 68 per cent of CO2 emissions) in commercial buildings. As windows dramatically affect HVAC performance, the glass industry is now playing a significant role in helping reduce energy consumption in buildings through improving the insulation and solar control properties of glass.
Historically, glass has ranked very poorly in the energy efficiency stakes - up to 12 times worse than a typical adjoining wall. Consequently, designing buildings with small windows or an array of obtrusive external awnings may be considered to satisfy the energy requirements. However, this approach is strongly opposed by building owners and users who want views, natural light and connectivity to the outside world. The answer is performance glass.
Current methods used to colour (tone), coat and glaze fabricated glass units have made significant inroads toward decreasing the thermal load within commercial buildings and reducing total building energy consumption.
Many Australian projects have demonstrated a measurable and direct link between performance glazing and construction and HVAC cost savings and also ongoing energy savings. Recently a builder completing an infrastructure project in Queensland investigated using a standard grey glass for a project instead of the Viridian Low E glass which was specified. Changing the type from a Low E to ordinary grey would have saved the builder $40,000. After consulting with the HVAC engineer, it was determined that the builder would need to pay an additional $145,000 in extra HVAC cost to compensate for the lesser performing glass if he used ordinary grey. In short, had the builder proceeded with the cheaper glass it would have cost him an extra $105,000. This demonstrates the critical and effective role that glass is playing in energy efficient design and real construction costs.
Performance glass does cost more than ordinary glass, but when combined with the savings made in HVAC and other considerations, in many cases performance glass actually reduces construction costs as well as reduce running costs over time.
New advanced glass coating technologies permit greater design flexibility while significantly reducing the solar heat load. This is achieved without sacrificing visible light or window size. For example, the triple silvering coating technology used on certain double glazed units reduces heat gain by 74 per cent through the glass and achieves U values that exceed standard triple glazing. This is remarkable considering the product remains almost completely clear.
Most Green Building Council design instruments require certain performance standards not only in terms of ultimate solar load permissible through the glass facade but also in visible light. By setting standards around visible light, building users are able to be less reliant on artificial lighting and in turn use less energy. Many traditional toned glass types may achieve the energy requirements in some climate zones but are too dark to comply with these higher standards. For this reason, the market pressure to produce new and more transparent glass types has been felt with domestic and overseas glass producers.
Sadly some designers who aren’t aware of these improvements may feel they have no other choice but to meet rising standards through formidable external shading, reducing the size of the windows or worse still, designs with no windows at all. Architects and building designers who are aware of the many recent improvements made to glass products have more flexibility in designing an energy efficient building rather than relying on traditional glass types and methods. Current glass technologies when integrated with good design can greatly reduce energy use and at the same time, increase the comfort levels for users within commercial buildings. This ensures that building users can continue to enjoy natural light, views and connectivity to the outside world without sacrificing energy efficiency.
Wade Bosse is commercial channel manager for Viridian Glass in Australia and NZ, providing technical support, training, product testing and glass innovation functions. Bosse has over 18 years experience in the commercial construction industry, is a member of the Green Building Council and also serves on the technical advisory board of the Master Builders Association in Queensland.
