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Solar Gain Calculations

What is solar gain?

All buildings absorb heat from the sun. The sun's heat is absorbed by and radiates through the glazing. Heat transfer via radiation depends on the material properties, the temperature gradient and the area or size of the surface.

In applicable terms, a window's solar heat gain is expressed as the solar heat gain coefficient. This number represents the window's ability to shade. The lower the number, the less solar heat is transmitted through the window.

Obviously if there is an obstruction between the Sun and a window, direct solar gain will be blocked. External shading devices usually work best because the gains are prevented from entering the space or zone in the first place.

To reach internal blinds, louvres or curtains, the solar radiation must have already passed through the window. Whilst it is blocked by the internal obstruction, it is still incident on that obstruction so its energy acts to increase surface temperatures. You will often find that, under direct sun, temperatures in the air gap between the window and blinds may be up to 20C higher than average internal air temperatures.

In many buildings a combination of external and internal shading systems are used, to comply with Part L of the Building Regulations with the internal blinds primarily there to combat glare at times of low sun angle. However, badly designed external shading devices may result in people actually closing the internal blinds to protect against direct sun penetration. When this happens, they typically turn on the lights to make up for a reduction in daylight levels. This means a double load: more gains to the space through solar radiation on the blinds and more electricity use from the extra lights and therefore a risk of the zone overheating.

Part L of the Building regulations requires internal gains from people and equipment to be taken into account when calculating solar gains in accordance with L2a clause 64.

Parry & Partners can provide manual calculations in accordance with CIBSE TM37 to comply with part L. For a free quotation please email drawings to or call 0151 524 0828.

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Solar Gain calculations throughout the UK.

If your looking for someone to provide your Building Regulation Part L compliance, Solar Gain calculations, feel free to get in touch. I pride myself in providing Solar Gain calculations to CIBSE TM37 in accordance with Part L2a clause 64.

National coverage for all Solar Gain calculations.

I can provide all your Solar gain and Building Regulation Part L compliance documents, whatever your postcode all areas are provided for as well as the surrounding counties in the Northwest such as Solar Gain Manchester, Liverpool Solar Gain, Wirral Solar Gain, Manchester Solar Gain and throughout the UK.

What is Solar Gains clause 64 of Part L2a...?

A window's solar heat gain is expressed as the solar heat gain coefficient. This number represents the window's ability to shade. Solar Gain Calculations are produced in accordance with CIBSE TM37 to comply with building control Part L2a clause 64. We provide Solar Gain calculations for all types of commercial building and provide a national service throughout the uk - Solar Gain calculations UK. We send you a PDF document to show compliance with Building Regulation Part L . No site inspections is required as the calculation is produced at design stage by a Solar Gain Assessor.

Liverpool Solar Gain calculations Manchester, Merseyside and UK

From the 1st January 2006 all new commercial buildings are required to have Solar Gain calculations. At Parry & Partners we can work together to develop a planned schedule to certify your proposed development with the required Solar Gain calculations for Building Regulation Part L compliance and can negotiate price on multiple developments.

Solar Gain calculation.

Most commercial premises now require Solar Gain calculations on construction or modification. Parry & Partners provide Commercial Energy Performance Certificate assessments and issue Solar Gain calculations. Energy assessor's must be a member of a government approve accreditation scheme. Parry & Partners produce Solar Gain calculations to CIBSE TM37 and commercial energy performance certificates on commercial buildings up to 150,000 sq ft. (level 4).