Energy usage in buildings explained
The urgency for substantial new power generating capacity as well as the reduction of current energy consumption levels in South Africa has become exceedingly evident over time.
The NERSA agreement, granting Eskom a 25% tariff increase per year over three years also places building owners in a very clear position – energy saving must be implemented now. The incorporation of passive energy efficiency measures in new buildings, homes and retrofits, is the most obvious starting point.
The newly legislated SANS 10400-XA: 2011 (November 2011) – which forms part of the National Building Regulations – is set to change the way we build in South Africa by governing energy usage in buildings. This is one of the initiatives being driven by the national Department of Trade and Industry, with the aim to reduce the country’s current energy consumption levels. In doing so, greater efficiencies on a long-term basis may be achieved as more time will be made available for new-build power stations to reach their full operational capacity, thereby changing energy usage patterns.
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- What is SANS 10400-XA?
- SANS 10400-XA, to a large extent, is based on and refers to SANS 204, which was first introduced in 2008 as a voluntary best practice guideline setting out the design requirements for energy efficiency in buildings and building services.
- SANS 204 stipulates the R-values – the measure of resistance to heat transfer – required for all elements in the building envelope – floors, walls and roofs (including ceilings).
- Recommendations for the ‘R-value” are based on the climatic conditions in particular locations. The deemed-to-satisfy provisions are based on climate zones, including dry bulb temperatures, thermal neutrality, humidity and southern coastal condensation risk.
- Objective of SANS 10400-XA
- The objective of SANS 10400-XA is to encourage and enforce the saving of energy in buildings – which are big users of energy at residential, commercial and industrial scale.
- SANS 10400 part XA essentially tackles how buildings are designed and built by addressing and providing guidelines for minimum requirements for things such as glazing, insulation, shading, orientation and building services, including air-conditioning, hot water and lighting.
- The regulations will eliminate the structural constraints which resulted in a major disconnect between what was in the best interests of building developer clients (i.e. fundamentally to build for the least cost and to rent for the most possible) and on the other hand undiscerning tenants and building purchasers, who are unaware that they are purchasing energy inefficient buildings and burdening their businesses in the future.
- How the objective of SANS 10400-XA will be reached
- This is done by imposing regulations to ensure buildings are built more energy-efficient.
- Plan approvals for all new buildings and building refurbishments where the window area amounts to more than 15% of the net floor area are dependent on the projects’ compliance with the requirements of SANS 204 and SANS 10400-XA.
- Evidence of compliance requires the backup of recognised certificates of performance from the manufacturers of respective products.
- Compliance must be substantiated with any building plan submitted to a municipality for plan approval.
- Requirements of SANS 10400-XA
- Regulations are compulsory and applicable to all new buildings and building refurbishments.
- Buildings with a window area of up to 15% of the net floor area are exempted, affording some leeway specifically for low-cost and government-subsidised housing.
- All new buildings erected after the 10th of November 2011 must comply with the new Energy Efficiency Regulations. Buildings will be classified according to the area in which they are to be built.
- In accordance with these areas, a thermal rating must be acquired. This will be done by sealing the structure and applying thermal insulation.
- All SANS 204 requirements are classified in terms of six different climatic zones across the country, and vary accordingly.
- Zone 1, described as cold interior, includes Johannesburg and Bloemfontein as major centres falling into this zone
- Zone 2 is described as temperate interior and includes Pretoria and Polokwane.
- Zone 3 covers centres such as Louis Trichardt and Nelspruit and is described as hot interior.
- Zone 4 being temperature coastal and includes areas such as Cape Town and Port Elizabeth.
- Zone 5 is described as sub-tropical coastal and this would include Durban, Richards Bay and East London.
- Zone 6 is described as arid interior and covers areas such as Kimberley and Upington.
- The use of solar geysers and/or heat exchange units will become compulsory.
- What makes buildings more Energy Efficient? / How long is Energy Efficiency Achieved?
- Design for climate as per climatic zones – while each of the six climate zones have different heating and cooling needs, the same principles of energy efficient design apply, with their application varying slightly, e.g. different levels of insulation or thermal mass.
- Building orientation – main living areas to the north to receive unobstructed winter sun;
- Internal planning to create zones which reduce the amount of energy required for heating and cooling;
- Fenestration (windows & frames) which are appropriately orientated and sized with protection from winter heat loss and summer heat gain, allowing for cross ventilation in summer for cooling;
- Thermal insulation in roofs, ceilings, walls and floors;
- Good draught proofing;
- Efficient hot water system and fittings, located close to user station;
- Efficient lighting and appliances;
- Landscape design that assists in modifying the microclimate for more comfortable conditions. New building products and materials are already being developed, and existing products are being modified and improved, to meet or better the performance requirements set out in SANS 204 and SANS 10400-XA.
- Benefits of SANS 10400-XA
- New buildings in SA will be some 30 – 50% more efficient than those built prior to 2012.
- These buildings will cost more as a result of the regulations being applied, but the extra cost would have a financial pay-back which was measured in a few months or years.
- Under the National Energy Act, 2008 Regulations on the allowance for energy efficiency savings Government Gazette no. 34596, companies can submit certificates of energy savings, issued by accredited persons, to SARS for a credit on their tax return. This government initiative further incentivises SA businesses to reduce their energy consumption.
- Interested parties will need to register with the South African National Energy Development Institute (SANEDI) and then appoint a measurement and verification professional to compile a comprehensive report on the energy efficiency savings achieved.
- This report will then be submitted to SANEDI who will issue that organisation with a certificate that can then be submitted to SARS who calculate the relevant tax return.