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Let the sunshine in

Let the sunshine in

By Ntsako Khosa
Bringing in natural light from outside without heat gain can be a complicated affair, however a mall in Klerksdorp sought to do it and achieved that balance.

Matlosana Mall in North West Province was designed with natural daylight in mind, this means that areas within the building must incorporate large skylight roof sections.

“Along with the increase of natural light flooding into the mail, came the usual problem of unwanted heat gain. In a bid to limit the influx of infra-red (IR) and near infra-red heat energy, the design team sought out the use of a solar reflective multiwall roofing panel system,” says Dayne Scrowther, architectural solutions consultant at Danpal.

Contracted from 2017, Danpal found the roofing in the mall was in trouble. “Their relatively new skylight roof appeared to be failing in every performance metric imaginable. Most notably was the amount of uncontrolled heat gain, afflicting the mall,” he says. He mentions that, the system was installed to prevent unwanted heat gain, however the malls HVAC system couldn’t deal with the high Solar Heat Gain Coefficient (SHGC) figures.

The system installed by Danpal was a polycarbonate multiwall roof sheeting system and was selected to provide a heat-free solution. Solid Green Consulting recommended a system that would meet a low SHGC value, to allow the current HVAC system to cope effectively. Scrowther explains that the translucent roof sheets would severely decrease the amount of light transmission into the mall. Before installing the roofing system an assessment of the roof was conducted by Solid Green.

matlosana mall 02Put their thinking caps on

Factors such as the ratio of skylights to the floor space, solar control of applied surface, infrared and near infrared versus visible light as well as the cohesive integration in implementation were factors that the team had to deal with.


Installation of the roofing sheets turned out not to be as simple as expected. Image: Danpal


When it comes to the ratio, the main area where the roofing system was installed acts as an open space atrium and has a high-volume of walk-through. “This busy space is covered by a near complete skylight roof, in industry standards, a veritable ‘greenhouse’. Careful consideration was needed to give the balance required between the amount of natural light transmission in LUX levels and the corresponding heat gain,” Scrowther says.

A favourable level between solar reflection and solar absorption had to be attained in order for the protection offered by the glazing material to be effective. The objective, “Is for the glazing material to move or redirect the heat energy away from the surface of the panel, back toward the outside of the building. This allows for the heat to dissipate back out into the atmosphere and prevents the transference of unwanted heat into the building, via conduction through the glazing system itself,” explains Scrowther.

The system aims to maximise natural daylight, therefore, Danpal had to implement a solution which would deal effectively with the infrared problem. “This type of light energy is the carrier of what we experience as heat and is closely related to the visible light spectrum. If a sufficiently developed solution to reduce IR and near IR without negatively affecting the visible light spectrum, is not introduced, heat gain will persist,” Scrowther shares.

The result

Scrowther notes that there was close cooperation between key role players such as green building engineers, architects and daylight specialists. The Danpalon multicell panel developed used a co-extruded low emissivity (low-E) treatment as well as a performance oriented reflective grey finish.

“This combination reduced the LT to an acceptable level, but most importantly, halved the infrared penetration through the translucent roofing. The result is a skylight roofing solution which matches the SHGC figure laid down by Solid Green, necessary for the existing HVAC system to operate effectively,” he says.

Matlosana Mall

The mall measures 65 000m2 in the town of Klerksdorp in North West Province. The site is roughly 20 hectares in area, flanked on the north side by the N12 highway and on the south by a seasonal wetland.

The design had to accommodate all major nationals, 265 shops, six movie theatres, a gym and an office component on the first floor. The brief also included a food court surrounded by restaurants and fast food outlets. The restaurants included covered and outside sitting areas. The site had to be developed with three future development pad sites, two full intersections from the highway and five parking bays per 100m2 of retail.

The mall design won the SAPOA Shopping Centres Category A Award in 2015.

 

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