Lighting and Acoustics Arch 353 Dr. Abdelrahman Elbakheit References اسس الانارة المعمارية, أستاذ الدكتور محمد عبد الفتاح عبيد.1 2. Architectural Lighting, M. David Egan and Victor Olgyay.

Quantity of Illumination: -Quantity of illumination on a work plane or surface is measured by What? -Work plane assumed as the plane that is 75 cm from floor level. -In cases where the work plane is different from this then we take the new level or position. E.g.. Black board, Electrical board, etc… Factors affecting the required quantity of light: -Good vision happens when there is high contrast between the work and the background. -Good vision happens with high level of illumination. -Duration time of Vision. -Quantity of work. From all of this the right quantity of illumination inside buildings needs research in all the above factors. In addition to this other physiological factors, the country location (sunny countries needs higher indoor light). Also Social, economical and nature of the place have an influence in illumination levels.

Recommended level of illumination: -British illumination society Recommends:

methods of designing building illumination: -The levels of illumination described above are for the whole of the space. -In some cases we may need some different tasks in the same space. Therefore the ways to design illumination can be as follows: -1.Design of General lighting for the whole of the space. -2.Design of specific or supplementary light in special parts of the space, as an addition to the light level there. -3.Decoration light, light is concentrated of special feathers inside the space to illustrate some aesthetic items in it.

Quality of illumination: -Depends of how well is the distribution of the brightness of surfaces in the space. -Reduction of glare, proper aiming at objects and proper colouring of the light to show the right object colours. -Proper choice to the method of lighting, the lighting fixture it’s suitability to the type of space and the economic factor in all of these. The main factors influencing the quality of light: -Contrast. -Glare and glare avoidance. -Good distribution and aiming of lighting. -Contrast: We can see objects because of the contrast between objects and their background. Therefore, contrast depends on brightness of the objects. Contrast = (brightness of the object - brightness of the background ) / brightness of the background Contrast = (reflection co-efficient of object- Reflection co-efficient of the background) / Reflection co- efficient of the background

Contrast = {specula Reflection co-efficient background ___ + spread reflection co-efficient background} {Specula Reflection co-efficient Object + Spread Reflection co-efficient Object} Over {specula Reflection co-efficient background + spread reflection co-efficient background} Glare: Is light in the wrong place. Reasons for glare: -Light source of high brilliance. -Dark vision field. -High contrast between objects and backgrounds. -Long exposure to high brilliance surfaces. Types of Glare: -Disability Glare. -Discomfort Glare. -Reflected Glare.

Glare Avoidance: -Use lighting fixtures that have low brilliance, reflecting surfaces to avoid direct beams in the field of vision. -Avoid high reflecting surfaces to avoid reflecting glare. Use tilted work surface. -Raise the lighting level of the background. -Good lighting design with good distribution and avoid adding more than the recommended light level. -Use light dimmers.

Good Lighting Aiming and distribution: -Good light distribution is a must to avoid dark areas in the field or vision.

Good Lighting Aiming and distribution: -Good light distribution is a must to avoid dark areas in the field or vision.