LIVING LIFE on the EDGE
Ballito is notorious for extreme humid summers, temperate winters and golden coastlines. The sun is the most powerful light source, and an inspiration of the name “Aurum”, which means gold and the nexus between nature and luxury. The sun is also a source of significant heat gain which is great for the temperate winter months but not during summer. Nexxagen sought to capture the benefits of the natural light for the clients’ and planet’s advantage.
Edge certification is awarded to a building if the required minimum 20% savings in operational energy, water and embodied energy in materials compared to the base case model is achieved. These efficiencies translate into a simple pass/fail system and indicate whether the building project has demonstrated the minimum efficiency.
Each stage of the certification consists of a two-round submission process to GBCSA. The Aurum project is at the preliminary certification stage and has completed round one with the EDGE auditors.
Nexxagen has inhouse EDGE experts and entered a contract with the EDGE auditor separately for the design audit (preliminary stage) and the site audit (post construction). It is recommended that a potential client uses the same EDGE auditor for both the design and site audit; however this is not a requirement.
EDGE certification begins during the design of the project (stage 0) and is subsequently brought to life by the design team.
The design team is briefed on the level of EDGE certification aspired to, processes, requirements and documentation required. It is vital to select a design team that is conscious of the planet and serious about reducing carbon emissions as it is, at times, daunting to meet the stringent requirements required for the standard. From this point forward, the team sets out to achieve the highest certification within the budget constraints of a successful project.
It is important to balance the lighting and ventilation benefits of glazing against the impacts of heat gain on cooling needs and/or passive heating. For example, heat is generally transmitted in the building at a higher rate through glass than through walls. The goal is to find the correct balance between the transparent (glass) and the opaque surface in the external façades helps to maximise daylight while minimising unwanted heat transfer, resulting in reduced energy consumption. Nexxagen has had a design goal to maximise illumination levels without significantly exceeding the solar heat gains in our warm summers, as well as to make the most of passive heating in temperate wintertime.
Windows are usually the weakest link in the building envelope as glass has a much lower resistance to heat flow than other building materials. Heat flows out through a glazed window 10 times faster than it does through a well-insulated wall. While glazed areas are desirable to admit solar radiation in a cold winter condition during the day, windows in warmer summer conditions can significantly increase the building’s cooling loads. With this consideration, Nexxagen’s design team selected the most balanced green measures to reduce the flow of energy between the building and surrounds.
Current technologies in the development exist to reduce water demand as well as recycle water and harvest rainwater for watering plants, swimming pools and other general purposes. There is a strong nexus between water and energy use. Energy is used to pump water, purify water to fixtures such as taps and faucets. Energy is also used to heat water. More heated water requires more energy. When efficient low flow shower heads and faucets are installed, there is an overall reduction in energy consumption. Water efficient fixtures and conservation measures typically have a short payback period and mitigate against the effect of climate change while future proofing the development against the impacts of water shortages and the demand on potable water. The rainwater storage systems combine captured water for later use, using rainwater reservoirs in underground tanks.
With environmental impact front of mind as well as reduction of associated carbon emissions and energy use, the design team meticulously selected sustainable materials, for example, selecting timber rather than glass for balustrading. Building lifecycle energy impacts have been considered. Currently, embodied energy is of relative insignificance, however, as energy consumption is driven down, the importance of embodied energy increases; this consideration is vital to future proof the development for the benefit of the next generation. Design modelling and simulation have assisted in controlling the form and surface areas of the building to make the most of natural sunlight and ventilation and to reduce the embodied energy in the homes.
MEASURING THE BENEFITS
An EDGE Zero Carbon Certificate is available in the operations phase for those that wish to attain it, with the prerequisite they have an EDGE Advanced status. Clients can now enjoy the benefits of certified green buildings with incentives that allow for rebates in rates and taxes linked to the level of EDGE certification achieved over the next few years. Smart meters throughout the homes will provide homeowners with measurable indicators of energy and water usage and how best to save energy and water.
• Offset energy and water costs with the ability to sell energy into the grid
• Improved and consistent indoor air quality
• Enhanced occupant health, comfort and wellbeing
• Higher sales and rental prices (home buyers will pay more for efficient homes with lower bills)
• Increased resale values
• Quick payback period for green measures
• Less maintenance costs due to quality construction
• Better occupancy rates
• Lower utility bills which can be used to offset the ever-rising costs of levies, rates and taxes
• Green mortgages minimise upfront costs and lower interest rates
• Reduced mortgage cost can finance green measures and innovative models can be explored to install them
• Certification provides quality insurance
• Decrease greenhouse gas emissions
• Extended equipment life due to less demand on the HVAC system and other appliances
• Capex costs are lower through the passive design of EDGE certified homes
• Passive designs have negligible costs but enhance the net-positive benefits