Restoring R-value in a historic landmark

by Darren
restoring r value

Constructed originally in the late 17th century, the Castle of Good Hope is South Africa’s oldest surviving building predating the Simon van der Stel era. It is an incongruous sight amongst the newer buildings of Cape Town. Yet within its four-metre thick walls there remains a substantial contingent of administrators, military personnel and tourism support staff.

Inside the massive outer-wall structure of the castle there has existed environmental workplace problems for many years now. Highly thermal, conductive dark-coloured roof material that was used in the original structure results in poor insulation properties covering the high thermal mass structure. This creates a cooking pot of alarming efficiency. Some years back planners addressed the problem by adding resin-bonded fibre insulation faced with foil under cement tiles. This brought a measure of relief to the building’s occupants. However, after 20 years the glass-fibre based material that was installed had collapsed and the material density went up while the R-values went down.

The formula that governs the relationship between R-value, material type and density is complex, but in essence a material’s thermal conductivity (the inverse of R-value) is proportional to its density. Therefore high density equals a good thermal conductor, but results in a poor insulator. This is why dormant air is a superb insulator. The best insulating materials are low-density substances that entrap a large volume of dormant air.

Solution to the insulation problem
The planners of a scheduled maintenance programme on the roof decided that replacement of both the insulation and roof tiles was the way to go. They approached various specialist companies, of which Eco-Insulation’s installer in Cape Town was one. In order to maintain the aesthetics of the building, the degenerating tiles were replaced with a Mazista slate.
An assessment of the situation quickly identified that the problem was all in the roof and the existing insulation no longer met the minimum standard R-values. Eco-Insulation products were pumped to the maximum possible depth of 110 mm in the roof. Eco-Insulation purged the old insulation from inside the roof space. The ceiling is a vaulted style, therefore sloping at an angle.

Eco-Insulation’s founder, Cecil Homan, developed and refined a unique pneumatic pump delivery system for insertion of the product into tight or inaccessible spaces. That is a major strength of the cellulose product and one of the reasons why it is the natural choice for this type of application. “The roofing tiles were removed from the crest of the roof, enabling the Eco-Insulation installers’ access to remove the non-performing old product and create a location into which the new product could be pumped,” he explained. “The process is extremely simple and 100% effective,” said Homan.

Homan says this project once again demonstrates the versatility of Eco-Insulation as a retrofit product. “With the advent of SANS 10400 XA, insulation has to comply with specific R-value requirements,” he said. “When working within tight recesses, such as the cavity between the sloped ceiling and the roof, Eco-Insulation can simply be pumped into place until the required depth is met.” According to him, the product distributes itself evenly into the space and mats, providing a very effective and enduring barrier against the movement of heat.
He said Eco-Insulation remains constant all year round and carries a lifetime guarantee. “Eco-Insulation can never become ineffective or deteriorate and will promote significant electricity savings,” Homan added. “The recovery period from the cost of Eco-Insulation is plus minus three years in energy saving.” 

Homan concluded that the product is fully approved by the SABS and it is fire-rated as to spread no flames above the ceiling. “Architects often forget about the sound-insulating benefits of the product,” he said. “This is very important for many industries such as hotels and retail outlets, where the noise levels need to be controlled and sonic absorption is required for effective acoustics inside the building.”

Tel: 021 555 3766
Fax: 021 555 3776
E-mail: eco-insulation@telkomsa.net“>eco-insulation@telkomsa.net

Pics: Photography by Gareth Griffiths Imaging

You may also like