REHAU Polymer (Pty) Ltd

Contact Information

Telephone: +27 (0)11 201 1300
Website: www.rehau.co.za
Country: South Africa
City: Bedfordview

Company Profile

THE REHAU SOLUTION FOR ENERGY EFFICIENT BUILDINGS

REHAU is a global manufacturer of energy efficient building solutions for the construction industry.  The company has vast experience in this field combined with a long standing presence in South Africa which it believes will benefit all those involved in meeting and exceeding the new SANS 10400XA Regulations.

In order to reduce the energy consumption of a building in an economical way you need to follow three principles of energy efficiency.

The first is to reduce energy losses in buildings by insulating and thermally enhancing the building fabric. REHAU’s PVC-U windows can play a significant role in this, with Uw-Values for double glazed frames manufactured using the REHAU Tritec PVC-U system as low as 1.5 W/m2K, vastly outperforming the aluminium alternative. These U-Values also allow extended glazed areas to be incorporated into buildings, increasing the use of daylight and in turn reducing energy consumption via artificial lighting.

The second is to distribute energy efficiently via water-based surface heating and cooling solutions.  In a market where conventional air conditioning is still the most common choice, REHAU is advocating a switch to concrete core tempering (also referred to as TABS) which reduces energy loads and delivers better comfort conditions for occupants.

The third and final principle is to generate energy efficiently, and this REHAU achieves by combining water-based surface heating and cooling with ground source energy systems and heat pumps.

Reducing Energy Losses

Although the South African fenestration market is still largely dominated by single-glazed aluminium frames, the advent of SANS 10400XA alongside SANS 204 is driving a shift towards PVC-U window systems because of the compelling thermal performance of PVC-U.

REHAU manufactures PVC profiles for the fabrication of energy efficient windows and doors that set new standards for thermal performance and distinctive design. From aesthetics to function and durability, REHAU products benefit from quality materials and the most advanced technology. In South Africa, REHAU focuses on the Tritec system which combines form and functionality.

REHAU carried out a Uw -Value analysis in line with the guidelines of the National Fenestration Ratings Council (NFRC) on a Tritec standard casement window (1230mm wide x 1480mm high, Fixed beside Side Hung) with a standard reinforced combination of Z sash, outer frame and T mullion.  The result demonstrates just how big an impact Tritec PVC-U frames can have in helping to meet the SANS 204 performance values.

Single glazed and with no coating, the REHAU Tritec window can achieve a Uw-Value of 4.5 W/m2K but double glazed and with soft coat glass, a warm edge spacer bar and Argon gas filling, it is possible to achieve a Uw-Value as low as 1.5 W/m2K.  

The extensive Tritec range meets the requirements for both refurbishment and new construction applications in residential and commercial buildings.

Distributing Energy Efficiently

Concrete core tempering involves embedding underfloor heating pipes into the concrete structure and transforming the floors and walls of a building into huge thermal stores.   Dubbed the ‘cathedral effect’, it relies on the high thermal capacity of the thick concrete walls to deliver both efficient heating and cooling depending on the seasons.

New Building Regulation SANS 10400XA sets challenging energy consumption levels for offices at between 185kWh/m2 and 210kWh/m2 per year.  In a new build market dominated by concrete slab construction, REHAU is advocating this innovative and energy efficient ‘concrete core tempering’ solution for both heating and cooling of the building which can help to achieve these targets.

The system works in a similar way to underfloor heating with cooling and heating water circulating through the arrays of PE-Xa pipe, pre-conditioning the temperature of the concrete structure and creating the potential for ‘limitless’ storage.  Used in conjunction with a supporting ventilation system, it can provide an energy efficient and cost effective alternative to full air conditioning strategies.  The supporting ventilation system can be designed just to provide the required fresh air supply, reducing both the initial investment and running costs.

There are huge benefits to be gained for both the contractor and the client from activating the storage mass in this way – most notably low investment costs, high levels of comfort and performance, ‘soft cooling’ with no draughts and the ability to reduce the output of other cooling devices.

The technology has been extensively proven across Germany and the US.  It was in Sacramento, California where an independent simulation study was undertaken recently to compare the different comfort conditions and energy demands of buildings using full air conditioning, underfloor heating, chilled/heated ceilings or concrete core tempering.  The results were overwhelmingly in favour of the concrete core tempering option, based on a reversible ground source heat pump and used with supporting ventilation.

Based on this study, for a typical office environment, concrete core tempering can be expected to reduce the energy demand by about 30% in comparison to full air conditioning with a conventional gas geyser and refrigeration set-up.  The energy demand can be reduced by around 60% when concrete core tempering is used in conjunction with a reversible ground source heat pump.

REHAU’s solution can be supplied either as pipework modules assembled off site on to pre-fabricated grids for when reduced installation time is required, or it can be installed on site for more flexible adaptation of the concrete core temperature control circuits for different building shapes.

Concrete core tempering has real potential as a cost effective means of meeting the requirements of SANS 10400XA. Concrete core tempering is already used extensively across Europe, China and the US in new commercial developments.  REHAU can assist in the design and specification and provide details to specifiers, consultants, clients and contractors of reference projects.

Generating Energy Efficiently

Ground source energy is one of the most commonly exploited renewable energy sources, relying on the near constant temperature of the ground throughout the year.  

A common misconception is that ground source energy comes from the earth’s core (geothermal energy) but it actually comes from the sun, with the earth acting as a huge solar collector.  At a depth of between 1.5 and 2m, the ground varies between 13 and 19ºC throughout the year and at about 20m deep, the ground becomes a constant 16ºC.
In order to extract energy from the ground a network of pipes is required which transfers heat into a ground source heap pump (GSHP).  This, in turn, converts the heat into usable energy for space heating requirements.  The typical Coefficient of Performance (COP) of a GSHP is around 3-4, which compares very favourably with non-renewable energy sources.  In reverse mode, the GSHP can be used for cooling which is of particular interest for commercial office developments.

Ground source technologies operate most successfully in conjunction with underfloor heating or concrete core tempering solutions which by definition require lower flow and return temperatures than conventional radiator systems, and REHAU always recommends that they are used in combination with one of these solutions.

Advantages of Ground – Source Energy Exploitation:

•    An economical source of energy largely independent of the weather or season
•    Substantial reductions in CO2 EMISSIONS
•    Energy savings of up to 75% for heating and cooling


For more information on REHAU’s energy efficient building solutions contact REHAU on (011) 201 1300.