Metzen Louvres Pty Limited
ABN 69 091 012 458
Unit 2/1B George Street, Mayfield East NSW 2304
( 1300 663 056 sales @metzen.com.au Fax: (02) 4960 3059
External versus Internal Shading Systems
European and Australian Studies
Many reputable studies have been conducted into the efficiency of external and internal shading systems. Most of the research has been carried out in Europe where high energy costs make effective insulation of glass areas a must - in fact some countries have tough legislation in place against energy inefficiency.
Research findings by Australian Institutions and summary figures are available through CSIRO.
The objective with any shading device is of course to keep the inside temperature in a range where our bodies feel comfortable and perform at their best.
It has been well established that these temperatures are ranging between 18º and 25º Celsius.
To achieve and maintain this comfort zone we have to spend valuable energy into cooling and heating our homes and workplaces.
Shading & Insulation
External shading systems that also act as barriers against cold winter nights, will save money in 2 ways:
1. The upfront investment into a smaller cooling and heating unit.
2. Ongoing savings in running and maintenance costs.
In case of an environmentally friendly design, cooling or heating may not even be necessary by using external shading and insulation devices (Olympic Village Design).
External Shutters Outperform Internal Shading Devices
Benchmarks set by the “German Industry Standard VDI” show external shutters to be outperforming internal venetian or vertical blind system.
External covers over glass areas with a northerly aspect stop over 85% of the heat whereas the internal systems allow nearly 5 times as much energy to pass.
To achieve and maintain the same temperature with internal shading devices, you need to invest twice as much into a larger cooling system.
It will cost on average 115% more to maintain and 140% more to run the larger unit.
Another important fact: In achieving these results external louvres reduce daylight only by 20%. (this figure is higher with roller shutters)
Limits of Internal Applications
To achieve similar cooling results internally the air between the glass and the internal blind needs exchanging up to 20 times per hour. In situations where the glass area is more than 65% of the total wall area satisfactory results cannot be achieved by means of internal solar control.
These results clearly favour external solar control systems. You also have the additional bonus of Security.
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