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Embodied Energy in the Home
Sustainable, "green," or environmentally friendly homes are usually associated with solar panels, LED lights, and energy-efficient appliances. Reducing the amount of energy our homes use and incorporating renewable energy sources are essential elements of lowering our carbon footprint. (Check out this Rise article for how you can easily calculate your carbon footprint).
However, what if we told you that the energy used in building the homes we live in often contributes much more to global climate change and other aspects of environmental degradation?
Embodied energy is not discussed often in conversations around the sustainable home sector. However, suppose we are going to commit to living in more sustainable and regenerative homes. In that case, we need to make an effort to understand the total energy footprint of the buildings we inhabit. Below, we look at what embodied energy is, how to calculate it, and simple things that every homeowner can do to reduce the embodied energy footprint of our homes.
Table of Contents
Climate Change and Resource Consumption Awareness
According to a 2019 poll released by Yale University and George Mason University, almost seven out of every ten Americans are at least "somewhat worried" about the threats posed by global climate change. For years, climate change was mostly seen as a distant threat that would have limited consequences, at least during the lifetimes of the current generation. However, extreme weather events are becoming a regular occurrence. And, more difficult scientific predictions regarding the scope and rate at which climate change is progressing have been released in recent years. This increased awareness has led to changes in attitude towards the most severe environmental challenge we face.
Despite this growing public concern, many people still feel relatively powerless regarding strategies to combat climate change. Flying less or purchasing an electric car can certainly reduce individual carbon footprints. Nevertheless, the homes we live in are often the most significant contributors to the carbon emissions associated with our lifestyles. The EPA states that in 2018, direct greenhouse gas emissions emitted from homes and businesses accounted for over 12 percent of total US greenhouse gas emissions due to their energy demand. So, investing money in energy-efficient, low-carbon retrofits for your home is a simple way to cut back on the "operational emissions" of your home over time.
But what about the energy used to build the homes that we inhabit? Say a homeowner went completely net-zero energy through installing a 7 KW solar PV system and investing in passive house retrofits. The energy used to source and transport the materials for that home would already have contributed to an enormous amount of greenhouse gas emissions.
In mathematical terms, embodied energy is measured by the quantity of non-renewable energy per unit of building material. The embodied energy of each material used in your home is conveyed in megajoules (MJ) or gigajoules (GJ) per unit weight (kg or ton) or area (m2). To try and make this a bit clearer, the Australian government has calculated synthetic rubber to have an embodied energy rating of 110 (measured in MJ per KG). At the same time, air-dried sawn hardwood has a rating of just 0.5 MJ/kg. The lower the score, the less embodied energy in the building material.
You can find a more detailed list of the embodied energy rating or the coefficient of a large number of building materials here.
What Can You Do to Lower the Embodied Energy of Your Home?
All this talk about mega joules might make you want to dig out your old high school chemistry book to try and understand how embodied energy is measured. Or, maybe advanced chemistry and math are not your things! Fortunately, several "principles of action" can help every homeowner reduce the embodied energy footprint of their homes.
Natural Materials over Synthetics to Reduce Embodied Energy
Synthetic and human-made materials almost always have a higher embodied energy footprint than natural products. For example, consider the embodied energy footprints of the following types of insulation according to the chart we referenced above:
- Cellulose insulation (cotton): 3.3
- Recycled sheep's wool: 14.6
- Fiberglass: 30.3
- Polyester: 53.7
Incorporate Recycled or Reclaimed Materials into Your Home Renovations to Reduce Embodied Energy
Homeowners should also attempt to incorporate recycled materials into their home renovation plans as often as possible. Many of these, like salvaged hardwood flooring, recycled paper countertops, are becoming much more accessible to source from mainstream manufacturers. These and other products containing recycled materials reduce the mining or acquisition of raw materials, a considerable component of embodied energy in building materials.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.
