Question 1

What’s room cavity ratio and room index ratio?

Accepted Answer

Room Cavity Ratio: Room Cavity Ratio (RCR) is calculated as: RCR = 2.5 * RCH * P / A. RCR = Room Cavity Ratio, P = Room Perimeter, A = Room Area. So RCR = 5 * H *(L+W)/(LxW)

Room Index Ratio: Room index (RI): a measure of the proportions of the room, for rectangular room. K = (L x W)/(L + W) * H. L = length of the room. W = width of the room.

Question 2

What’s the relationship between room cavity ratio and room index ratio?

Accepted Answer

According to the calculation formula, Room index multiply by Room cavity ratio always equals 5. In fact, these two coefficients both reflect the utilization factor of the lamps in the space, only there is a difference in the calculation method. The larger the RCR calculation result, the smaller the utilization coefficient of light in the space is, and the LPD can be increased appropriately. The larger the RI calculation result, the larger the utilization coefficient of light in the space is, and the better the lighting result is (with the same lamps and the same distribution).

Question 3

What’s LPA which differs from LPD?

Accepted Answer

LPD (Lighting Power Density) is the amount of lighting power per unit area and is often used to measure the energy efficiency of a lighting system.

LPA (Lighting Power Allowance) is the upper limit of lighting power according to an energy efficiency standard (e.g. ASHRAE 90.1) LPA is based on the limit of LPD (e.g. 1 W/ft²) by the space-by-space method or the whole building method for calculating the building's lighting power allowance for the year.

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LED Street Light

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LED High Bay Light

High Mast Light

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LED Tunnel Light

LED Garden Light

LED Canopy Light

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Lighting Accessories

Smart Systems

Simulation Design

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