Energy efficient buildings have been seen as a luxury rather than a necessity in some countries. With many countries worldwide introducing new legislation to improve on the total building energy-efficiency footprint, it has prompted for an essential holistic look at building processes. Leading aluminum extrusion manufacturers have taken this environmental requirement to heart and have introduced thermally efficient window systems which, along with their other products, comply with national standards.
Conservation of energy is of serious concern in building design as a large amount of energy is expended in the heating or cooling of interior spaces. One of the priorities is to cut down on the internal illumination by increasing glazing to allow for increases in ambient light. This however increases the heat loss or gain to these spaces as windows and doors can notoriously be bad insulators.
Energy-efficiency in building and in particular glazing systems has been reserved mainly for cold climate zones and this has been the obvious costs involved in heating buildings. Now, the costs involved in cooling buildings are becoming just as apparent. As important as it has been to keep heat from going out of a building, it is becoming as important to ensure that heat coming into a building is limited.
The U-Value Measurement is used to evaluate the thermal performance of building material. Simply put: U-Value is the measure of the rate of heat loss through a material. Thus in all aspects of home design, the lowest U-Values should be aimed for where possible because the lower the U-value, the less heat that is unnecessarily escaping or entering.
Energy (temperature) flows through glazed windows and doors through a combination of four main factors namely: air leakage, conduction, convection and radiation.
• Air Leakage
The flow of temperature through (in or out) the product through unsealed opening frames. Some windows do not have any seals, making them non-compliant to building regulation and extremely inefficient altogether.
The process by which heat is directly transmitted through a substance where there is a difference of temperature.
The movement caused within a fluid or air by the tension of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequentially results in the transfer of heat.
Heat transferred in the form of light energy through glass (including non-visible spectra).
Both clear float glass and aluminum are reliably poor insulators of heat. In buildings, they equate to a large portion of the energy required to maintain optimal environmental conditions. Designing an Aluminum Glazed System to overcome all four heat transfer conditions is paramount to enhancing the saving of energy which can be achieved all year around.
Aluminum: Aluminum being non-transparent is affected by radiant energy by absorbing it and converting it into both conductive and convectional heat. Aluminum is one of the best heat conductors and because of these properties it is used as a heat sink in computer thermal applications. Controlling the conductive and convection properties is important and possible when designing thermally efficient systems.
Glass: Glass being transparent is not greatly affected by radiant heat as it allows heat in the form of infrared radiation to pass directly through it, heating a room directly. It is also a poor insulator from both conductive and convection properties.
Glazed systems are a major building cost. Thermally-efficient glazed aluminum systems have the benefit of paying for itself. As energy costs increase, the energy saved though efficient building practices actually put money back in your pocket in the long-term, effectively paying for themselves.
Building designs in certain countries are starting to feel the effect of inefficient building energy design due to increases in energy costs. By changing the design configurations of both aluminum and glass and adding insulating weather seals, it is possible to substantially modify and convert these materials into an effective energy-efficient system. On their own they remain inefficient, but in a system designed to isolate and modify the energy flows, they become highly energy-efficient fenestration systems.