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Embodied Energy in Building and Construction

John Herbert, hong kong energy saving expert, BEAM expert
John Herbert

For building and infrastructure projects there are essentially two types of GHG emissions related to buildings, embodied energy (embodied carbon) and operation energy usage, together also known as whole carbon. Embodied energy (embodied carbon) is important because most systems currently overlook embodied energy so you could gain an unfair advantage.

To discuss embodied energy in buildings call John Herbert 2335 9830 today!

For buildings and infrastructure project Embodied Energy (embodied carbon) is the accumulative energy used and resulting GHG emitted consumed creating the materials/products used to construction.

In Hong Kong, because the majority of construction materials are imported, so the manufacturer needs to provide an environmental product declaration, listing the embodied energy/carbon in their product/material for assessment.

embodied energy, embodied carbonCredit: World Green Building Council - Click for larger image

Globally, embodied energy (embodied carbon) accounts for approx. 11% of the total building GHG emission, that provides opportunities to lower embodied energy (and embodied carbon) earlier and faster.

To discuss embodied energy in buildings call John Herbert 2335 9830 today!

Embodied Energy (embodied carbon) is calculated from the energy used to mine, process, assemble, manufacture products and transport to the job site.

Since the energy has already been consumed it is called embodied energy (or embodied carbon). That energy has been consumed and is forever tied to that product or material, from factory door to its grave. That is important in terms of construction wastage, if the material is delivered to site, but damaged so it is abandoned, the embodied energy is already consumed and must be counted.

Like it or not, sustainability and energy use are opposite sides of the same coin.

Embodied Energy in Building Structure

The term Embodied Energy is meant to reflect the energy consumed during production stage of products/materials, in the Hong Kong context, that predominantly means reinforced concrete, glass, aluminium, and steel.

The production of the concrete, glass and steel require vast quantities of energy, and emit carbon dioxide emissions during those processes, therefore the embodied energy (embodied carbon) is relatively high.

There are few industries remaining in Hong Kong therefore the majority of construction materials and constituent raw materials are generally imported from overseas.

For buildings using cast-in-situ reinforced concrete, the constituents are imported, then either mixed on site in a batching plant (for large projects) or mixed in a central concrete plant and transported using concrete trucks to the site.

embodied energy building

Embodied Carbon and Production

Steel and the constituents materials for production of cast-in-situ concrete are energy intensive, the raw materials typically produced overseas and shipped to Hong Kong, therefore the resulting carbon emission does not appear as a local emission, and the Hong Kong GHG inventory appears low, and that energy used in production is tied to that product/material, and embodied energy is the term used to define those emissions.

In a perfect world all the materials would arrive with embodied energy label (environmental product declaration) totalling up those energy use figures provides the total embodied energy figure, but real life is rarely that straightforward. It is certain that the process will improve as more stakeholder learn and adopt a common process.

Take one material for example steel, it can be provided by different factories in different countries, each with a different embodied energy and the data is often difficult to obtain.

Then some materials for example concrete comprise several different elements, which maybe be sourced from different countries. Often one project will have steel and concrete materials from a number of countries, with different production methods and travel distances.

At the time of writing, the biggest issue is the lack of an open and transparent database, so everyone is on the page.

Embodied Energy in Waste

After the useful life of a product or material it is often sent to landfill, including the embodied energy (embodied carbon) used in its production.

Therefore one way to reduce emissions would be the use of post consumer waste as a raw material, including building waste, where possible materials should be re-purposed, some examples:

- waste concrete, a free resource,can be used as a raw material for producing new concrete paving blocks (pioneered in Hong Kong);
- waste glass (cutlet), a free resource, can be used as a raw material for producing new glass, and used as replacement for silica for producing concrete paving blocks;
- waste gypsum board, a free resource, can be used as a raw material for creating new gypsum board, and can be used as a conditioner added to soil;

embodied energy

BEAM PLUS EU3 v1.2 Embodied Energy

The EMSD LCA tool provides the calculation software to estimate the embodied energy in Hong Kong building structures, and BEAMPLUS New Building, credit EU3, encourages embodied energy assessment at the concept stage, giving vital knowledge to designers before key decisions are made.

Under BEAM PLUS EU3, if two or more options are examined, and the option having the lowest embodied energy is chosen, a bonus point can be earned.

embodied energy, embodied carbonembodied v operation energy ratio - Click for larger image

At some future date we expect the electricity grid will be increasing decarbonised, therefore the operational energy used in the buildings will also decrease, so the importance of embodied energy, at the beginning of the project, is important and cannot be overlooked.

Early Is Better

Whilst it is true that embodied energy (embodied carbon) for a building can be calculated at different stages of the project, after the design is complete is too late to influence the embodied energy (embodied carbon). Earlier is better, with greater impact on the project, as shown on the UKGBC chart below.

Low Carbon Materials

There is a misconception that it is easy to pick a low carbon products, but that overlooks its application, for example, the embedded energy used making a typical brick is high, yet a brick could last 200 years. A timber door set might be low carbon but must be replaced several times during the building lifespan. Context matters.

embodied energy, embodied carbon, early is betterCredit: UKGBC Impact on the design process - Click for larger image

Having the embodied energy (embodied carbon) data, with Environmental Product Declaration sheets, early can be a quick win, influencing the choice of materials BEFORE selecting the final construction materials.

To learn more about embodied energy call John Herbert on 2335 9830 today!

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tags: embodied energy, embodied carbon, GHG, carbon emission, embodied-energy , embodied-carbon, carbon emission

date: 20-01-21