CSIR unit concludes passive energy efficiency study, moves to continue research

23rd August 2013

By: Samantha Herbst

Creamer Media Deputy Editor

  

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The Council for Scientific and Industrial Research’s (CSIR’s) Built Environment unit has signed its second memorandum of understanding with chemicals giant BASF to continue researching passive energy efficiency in new buildings.

The CSIR concluded a two-year performance research project earlier this year, which analysed the energy and thermal performance of an insulated demonstration house, sponsored by BASF, through data collection and thermal modelling.

The research involved measuring actual temperature readings inside the house and modelling the energy and thermal performance of the building to establish the thermal comfort and energy efficiency of a highly insulated building system. Temperature data collection took place from December 2011 to April 2013.

“We installed data loggers, which recorded data every 15 minutes for an entire year. BASF also made a weather station available to us, giving us access to on-site weather data with which to measure the performance of the building in local weather conditions,” says CSIR Built Environment senior researcher Llewellyn van Wyk.

Erected by construction company Helm Construction at the CSIR’s built environment innovation site, in Pretoria, BASF’s 40 m2 demonstration house was built using the Agrément-certified Imison system – a composite walling system that combines expanded polystyrene, light-steel framing and sprayed-on concrete.

Alternative Insulation Technologies
The aim of the study was to measure the abso- lute temperature performance of a standard building comprising a roof, floor and walls and using an alternative insulation technology, based on BASF’s expandable graphite- impregnated polystyrene, Neopor, which improves insulation in newly built and renovated properties.

BASF Holdings South Africa MD Dr Dieter Kovar says the company collabo- rated with the CSIR Built Environment unit to demonstrate the need for insulation in maintaining comfortable indoor living temperatures.

“Although this test case was aimed at measuring the effectiveness of Neopor in the southern hemisphere, BASF’s cool paints technology also contributed to findings at the demonstration house,” says Kovar.

The house was also fitted with double-glazed windows and doors, which is unusual in low-income housing. However, Van Wyk explains that, for the purposes of the exercise, the CSIR wanted to improve the building envelope as much as possible to determine the value in different technological interventions.

Results of the Study
The CSIR study indicates that the BASF demonstration house will require minimal heating in winter to maintain a comfortable indoor environment, as the measured indoor temperature was within a comfort zone of between 19 ºC and 28 ºC for most of the study.

Van Wyk explains that, while the building reached a comfort level of below 19 ºC for a very short time during the study’s timeframe, the temperature within the house was generally too hot and ran above a comfort level of 28 ºC in November and December – South Africa’s hottest months.

He notes, however, that the door and windows of the house remained closed for the duration of the study to ascertain how the building would react to outside temperatures without human interference.

“The moment the door and windows are, however, the building immediately discharges the heat,” he says, further explaining that, as a light construction that does not contain thermal mass, the walls of the BASF demonstration house do not retain heat. Therefore, cooling can easily be achieved through natural ventilation.

The study further concluded that, in terms of yearly space heating expenses, the BASF demonstration house would cost owners R567/y using a conversion rate of 1 GJ/278 kWh, at a killowatt-hour rate of R1.20.

This proved significantly less, compared with two benchmark houses also constructed on site by the CSIR’s Built Environment team – a typical low-income house and a SANS 204-compliant house, with yearly heating costs of R4 082 and R2 553 respec- tively.

“Therefore, space heating costs could be significantly reduced in a residential building such as this, saving owners close to 80% in yearly heating costs, compared with a SANS 204-compliant house,” says Van Wyk.

He adds that this inevitably contributes to a healthier environment when one considers alternative forms of heating such as paraffin heaters.

Van Wyk’s team further calculated that the BASF structure would require significantly less water for electricity-generation purposes, revealing that a typical low-income house requires 4 500 of water a year to generate electricity, while a SANS 204-compliant house requires 2 800 of water a year as a result of its electricity consumption.

The BASF demonstration house, however, only requires 371 of water a year, which proves that driving down the energy demand of a building has a significant impact on the amount of water needed by a power utility to provide electricity.

“In a water-constrained and energy- challenged environment, these findings are significant,” says Van Wyk.

He hopes that the data produced by the CSIR’s Built Environment team will support specifiers and architects in determining insulation requirements, especially in the Pretoria central region.

Meanwhile, despite its many benefits, the BASF demonstration house costs R90 000 to construct, excluding value-added tax, which is significantly more than the current low-income housing subsidy amount of R68 000.

However, the study has been acknowledged by the CSIR and BASF as a breakthrough experiment and it will be a significant resource of information as government embraces alternative building technologies, which it aims to implement in 60% of its upcoming social infrastructure build programmes.

Edited by Martin Zhuwakinyu
Creamer Media Senior Deputy Editor

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