Parametric Studies on Window-To-Wall Ratio for Day lighting Optimisation in High-Rise Office Buildings in Kuala Lumpur, Malaysia

Abstract

The use of daylight in non-residential buildings has become an important strategy to improve
environmental quality and energy efficiency by minimising artificial lighting requirements
and thus reducing the cooling load. These can be achieved by a good and proper configuration
of the fenestrations. They can control the amount and distribution of natural lighting entering
a space as a pleasant daylight strategy. There are some Passive Design factors which
architects should consider, namely: fenestrations, climate conditions, orientations, and
shading devices. This paper studies the impact of Window-to-Wall Ratio (WWR) as one of
the passive design strategies to optimise day lighting in high-rise office buildings in Kuala
Lumpur as a recommendation for building designers to use it at the early stages of design.
This study was carried out by simulations on IES-VE software by using RADIANCE program
for calculation of the daylight distribution due to WWR on daily basis during office hours. An
investigation on the optimum amount of window size has been done by studying an office
room model with 6m × 6m × 4m dimension. WWR was considered from 20% to 50% at 5%
interval in two types of expanding method of window namely vertical and horizontal. The
simulations were performed in two sky conditions (Sunny sky and standard CIE overcast sky)
on different dates, times and orientation. The primary findings of this study found that 25%
WWR is the best in vertical expanding as well as 35% WWR have more suitable daylight in
horizontal expanding in sunny sky for a hypothetical office room