Executive Summary
Wall grazing and wall washing are two different methods that are used to illuminate a wall, but achieve the same goal very differently. This assignment compares the outcome of wall washing vs. wall grazing in a room that is 25' wide x 75' long x 24' high. For the purpose of this assignment we will be lighting the vertical wall that is 75' x 24'. To ensure that we look at a broad scope of luminaire options, I will be preforming three calculations for wall grazing and three calculations for wall washing. Each calculation will use a different lamp type so that it can be seen how the outcomes compare when the source is changed. For the wall washing calculations a linear fluorescent, an LED, and a metal halide lamp will be used, and for the wall grazing calculations a linear fluorescent, an LED, and a halogen lamp will be used.
In order for a wall to be considered grazed the luminaire is placed somewhere between 0' and 2' away from the wall that you are trying to illuminate. A wall is considered washed when the fixture is placed one-third of the height of the wall that you are illuminating away from the wall. For this assignment in order for the wall to be washed with light it should be placed approximately 8' away from the 24' tall wall that we will be illuminating.
Since it was difficult to find variables to keep constant, I decided that all of my luminaires would be placed 8' from the wall for all of the wall washer calculation. I also kept the distance from the wall constant for the wall grazer calculations as well, except that these calculations were placed 0' away from the wall (right against the wall).
Another variable that I was able to keep constant is the amount of fixtures that were used. For the wall washer calculations I always had 18 luminaires that were spaced 4' o.c. and were a distance of 3.5' away from the side walls. While the wall grazer calculations did not have a fixed number of luminaires that were used, they did have a fixed length. All of the wall grazers in the calculations ran the whole 75' of the wall.
By keeping the distance of the fixtures, the number of fixtures for the wall washers, and the run of the fixtures for the wall grazers the same, I was able to see how different sources of light affected the illuminance values on the wall.
I found that for the wall washer fixtures the metal halide lamp had the greatest amount of input Watts and that it was approximately seven times the amount of input Watts for the linear fluorescent and LED fixtures. I also found that for the wall grazer fixtures the halogen and LED fixtures had approximately 2 times the amount of input Watts that the linear fluorescent fixture had.
When looking at the illuminance values of the wall washers the metal halide ended up with the greatest illuminance values in the minimum, maximum, and average illuminance categories. Surprisingly the LED fixture had the lowest illuminance values in all three categories. However if we are to look at the wall grazer category the LED fixture produces the highest illuminance values in the three categories.
At the end of all the calculations we can see that the wall washer luminaires distribute the light across the walls more uniformly than the wall grazer luminaires. With the wall grazer luminaires we can see a hot spot near the source, and a big drop off in illuminance values near the floor.
In order for a wall to be considered grazed the luminaire is placed somewhere between 0' and 2' away from the wall that you are trying to illuminate. A wall is considered washed when the fixture is placed one-third of the height of the wall that you are illuminating away from the wall. For this assignment in order for the wall to be washed with light it should be placed approximately 8' away from the 24' tall wall that we will be illuminating.
Since it was difficult to find variables to keep constant, I decided that all of my luminaires would be placed 8' from the wall for all of the wall washer calculation. I also kept the distance from the wall constant for the wall grazer calculations as well, except that these calculations were placed 0' away from the wall (right against the wall).
Another variable that I was able to keep constant is the amount of fixtures that were used. For the wall washer calculations I always had 18 luminaires that were spaced 4' o.c. and were a distance of 3.5' away from the side walls. While the wall grazer calculations did not have a fixed number of luminaires that were used, they did have a fixed length. All of the wall grazers in the calculations ran the whole 75' of the wall.
By keeping the distance of the fixtures, the number of fixtures for the wall washers, and the run of the fixtures for the wall grazers the same, I was able to see how different sources of light affected the illuminance values on the wall.
I found that for the wall washer fixtures the metal halide lamp had the greatest amount of input Watts and that it was approximately seven times the amount of input Watts for the linear fluorescent and LED fixtures. I also found that for the wall grazer fixtures the halogen and LED fixtures had approximately 2 times the amount of input Watts that the linear fluorescent fixture had.
When looking at the illuminance values of the wall washers the metal halide ended up with the greatest illuminance values in the minimum, maximum, and average illuminance categories. Surprisingly the LED fixture had the lowest illuminance values in all three categories. However if we are to look at the wall grazer category the LED fixture produces the highest illuminance values in the three categories.
At the end of all the calculations we can see that the wall washer luminaires distribute the light across the walls more uniformly than the wall grazer luminaires. With the wall grazer luminaires we can see a hot spot near the source, and a big drop off in illuminance values near the floor.