Blog: Natural Light as a Tool for Sustainable Building Design

Exterior of home with natural lighting.

In the photo: The exterior of a home Meeta Awasthi Morrison designed to incorporate natural lighting.

Meeta Morrison, UT Alumnus of the Masters of Architecture program, presented a talk to the UT New Color Class about color in architecture during Spring 2020. A key feature of the talk was the integration of sustainability in her designs, specifically through the utilization of natural light. Students responded to the talk with eager questions and exciting ideas for how to transform their own spaces. With this positive response in mind, Meeta has provided a condensed version of the talk for those who could not attend. Many UT campus buildings built over the past 10 years, including the new Engineering Education and Research Center (EERC), utilize natural light to reduce energy costs. Meeta shares how natural lighting can be used in residential situations as well.

Blog post by Meeta Awasthi Morrison AIA NCARB, UT-Austin School of Architecture alumnus

Natural light in a space can be transformative both aesthetically and as a catalyst for sustainable design. When we talk about sustainability and how it applies to the design of buildings, the conversation often goes directly towards, solar panels, electric cars, battery backup and other cool gadgets. These are all great strategies for creating energy efficient, modern buildings that can reduce energy consumption and sustainable material choices can lead to better indoor air quality and a smaller carbon footprint, but thinking about how to best bring natural light into a building is an overlooked and very important guiding principle for a more sustainable building.

It’s a well-known fact that in the northern hemisphere larger windows with overhangs on the south, larger windows on the north and limited opening on the east and west are the best strategy for modulating the quality of light in a building, reducing heat gain in the summer, and thus reducing energy consumption. This passive strategy is great when the building is located on the ideal lot facing exactly the correct direction, but what happens when the situation is a bit more challenging? Most urban and even suburban dwellers don’t have the option the change the location of the lot or the orientation of their house. Even with these constrains, it is still worth examining how an understanding of the site can lead to better design.

The existing house in this Austin neighborhood was oriented eastwards facing the street. The back and front of the house were the only places that there were any windows. In the daytime a lack of natural light created a perpetually gloomy interior. In the evening western sun entered the spaces, creating annoying glare and hotspots in the poorly insulated house. The house could not be turned, so an examination of the site and a thoughtful expansion used the advantages of the site to allow more natural light in the interior of the house.  create more shade, capture natural cooling breezes and reduce energy consumption. 

The existing lot slopes down steeply from the highpoint at the southwest corner to the low point in northeast corner. The hill continues up beyond the property line in the back. A line of mature oak trees at the back-fence line reached an elevation close to 45 feet above the existing finished floor of the house. This vertical baffle filtered a lot of strong sunlight in the hot summer evening. However, a large existing concrete patio at the back of the house was serving as a heat sink and baked all day while the sun was high in the sky, only to release the heat to the house in the evening. Breezes in Austin tend to be from the south but, on this lot in the evening were modulated by the direction of the slope and ran downhill from the southwest. The breeze was also affected by the lack of building on the southeast corner of the lot, intensifying as they sucked through the low-pressure area.

A plan was developed to expand the house towards the back to take advantage of the vertical shading and breezes from the hill. This allowed for a move to open up the back wall with floor to ceiling glass. A new studio and office addition are angled strategically northward to capture ambient light and became the driving design factor. The height of the studio further helped to shade the new wood deck, which sits above grade allowing for the ventilation and also shading of the foundation. Inside the studio, the faceted ceiling and non-orthogonal plan helps to diffuse and soften the light. New windows throughout the house on the north and south sides of the house provide views of the newly landscaped garden and allow natural light into the house from all directions.

The house was remodeled with the Austin Energy Green Building program and achieved a 5 star-rating. A whole house insulation envelope and careful attention to the HVAC system to heat and cool but also control humidity were designed to reduce energy consumption. Local, sustainable, durable materials, low VOC finishes, low water consumption fixtures and reduce-reuse-recycle strategies were implemented to achieve a greener building. 

At the outset of the design the architect must understand the site, its orientation and its topographical peculiarities, the characteristics of the soil, the pattern and density of the vegetation and its micro and macroclimate. Attention to these unique characteristics of the site can lead to holistic solutions that not only create better buildings from the perspective of energy and resources, but buildings that are illuminated with natural light which can positively affect the mood and wellbeing of its occupants. The primary goal for this house started out as a desire to get natural light into every room of the house but it also led to a global solution that created a more sustainable building.