Assessing the invisible energy

Linda Hildebrand: “50 percent of our resources are consumed by the building sector.” (Photo: Tomas van Dijk)
Linda Hildebrand: “50 percent of our resources are consumed by the building sector.” (Photo: Tomas van Dijk)

Name: Linda Hildebrand
Nationality: German
Supervisor: Professor Knaack
Subject: Embodied energy in buildings
Thesis defense: In ten months

“Roughly put, I’m interested in energy and buildings. It is remarkable that, globally, 50 percent of our resources are consumed by the building sector. This means that the building sector has huge potential but also has an important responsibility in reducing our ecological footprint. Because building owners want to reduce their energy costs, optimization of buildings’ energy performance during their utilization is well on the way. However, the energy a building consumes for heating, cooling, ventilating and electricity represents on average only half of the building’s energy impact over its whole lifecycle.

A significant part of energy consumed by a building is embodied energy in building materials; or in other words, energy consumed in the acquisition of raw materials, their processing, manufacturing, transportation to site and construction. Similarly, energy is also needed at a building’s end of life for the demolition, recycling, incineration and so on of building materials. The challenge with embodied energy is that it is invisible to the eye. When you look at a building, you cannot see or feel the embodied energy. This makes it hard to understand for someone who does not know the mathematics behind it.

And the mathematics of embodied energy isn’t that straightforward. There is no ‘one-size-fits-all’ solution to optimize embodied energy in building materials; there is no one unique best material. Embodied energy has to be considered comparatively. It’s not so much the absolute amount that counts but how well it is utilized. This will depend on various factors, such as the life span of the building and the function of the building materials. So, what is important is to consider embodied energy early in the design process.

My PhD aims to enable architecture designers to integrate embodied energy considerations in their design. I developed an energy performance assessment tool based on an assessment I conducted on 50 buildings. This tool allows designers to for example compare different scenarios with different building materials. Moreover, it shows where there is the most space for improvement.

For instance, I found out that approximately one-third of buildings’ embodied energy lies in their structure. However, there is not much you can do about the structure; whether it is steel or concrete does not make a significant difference in terms of embodied energy. In contrast, facades can represent up to half of the embodied energy in a building or much less. Façades thus have the most potential for change.
In short, my PhD is about supporting architecture designers in making smart decisions for a more ecological building. In fact, it’s very nice, because I’m already putting into practice the findings of my PhD in my part-time freelance consultancy work.”