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Embodied Energy in Building Construction

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


The materials and components used to create new buildings required the use of energy to mine, process, assemble, and manufacture and delever to the job site. Its important because the majority of materials and components are imported.

That energy has already been consumed, so we call it embodied energy, it is like an energy millstone permanently tied to the product or material, once the energy becomes embodied, it already used it is used forever. For a reversible material such a ferrous and non ferrous metals, additional energy is embodied during the recycling of the material.

EMSD LCCA software tool provides the energy embodied data for a range of materials used in construction industry that can be employeed to calculate the total embodied energy.

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

Buildings and Energy

The term Embodied Energy is meant to reflect the energy consumed during the production of materials and components. For construction industry we focus on the building structure, predominantly reinforced concrete (RC), glass curtain wall, and steel are used in Hong Kong

The production of theses core materials such as concrete components, glass, aluminium, and steel, all require vast quantities of energy to produce creating carbon dioxide emissions in the process.

In Hong Kong there are no factories, so materials such as glass, aluminium, steel must be imported from overseas.

Most of Hong Kong's buildings are constructed using reinforced concrete, are either cast-in-situ, and the limited use of prefabricated sections delivered and installed on site.

Reinforced Concrete Cast-In-Situ
The materials for producing reinfored concrete are generally imported and locally mixed, either on site in a batching plant for large projects or mixed at concrete plant and transported to site using concrete mixer trucks. And the rebar for cast-in-situ the reinforced concrete must also be imported.

The embodied energy for prefabricated components are similar to other imported components in that the locally used energy cost is imported with the prefab work.

One challenge for dealing calculating Embodied Energy with imported materials not covered in the emsd list is the reliance on Embodied Energy declarations because different countries have different standards.

building embodied energy building report

Embodied Carbon and Production

Steel and the materials for making concrete are energy intensive, typically produced overseas and transported to Hong Kong, therefore the related carbon emissions do not appear in the local inventory. Therefore publishing the embodied energy and embodied carbon used in buildings should be encouraged provides a better picture of Hong Kong emissions.

In a perfect world all the materials would arrive with emodied energy label, totalling up those figures provides the emodied energy figure, but real life is rarely that straightforward.

One element for example steel, 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, could be sourced from several different countries. Often one project will have steel and concrete materials from a mumber of countries, with different production methods, and tranportation distances.

Like it or not, sustainability and energy are two sides of the same coin

-- John Herbert



Embodied Energy in Construction and Demolition Waste

It is often overlooked, after the useful life of a product or material it is sent to landfill, including the embodied energy millstone already used in its production.

Demolition of the building or structure does not release the embodied energy, the energy already used in the creation of the components and materials, is tied to that material forever.

As one US carpet manufacturer pointed out, its source for raw materials is under the feet of its customers



Under the post consumer waste, post demolition waste should be included, is important, where possible, that so called "waste" material is not viewed as waste but as raw materials to repurposed. 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 (cullet) - a free resource, can be used as a raw material for producing new glass. Also used as replacement for silca 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;

ferrous metal - a free resource, reversible, can be melted down and used for creating new steel and new steel products;

aluminium (curtain wall) - a free resource, reversible, can be melted down and used for creating new aluminium products;

building embodied energy reports



With the neccessary expertise for example specifying energy, water and waste efficient techniques and equipment in buildings and infrastructure and the specialist analysis techniques to demonstrate the practical environmental performance Kelcroft prepares embodied energy studies and reports for developers and building owners.

Providing embodied energy data to designers, it is hoped that the information will influence the choice of materials BEFORE commencing the pre-design/design stage because after the key decision is made the embodied energy is essentially fixed forever.

Emodied energy can be influenced, for example choosing lower volume of higher strength reinforced concrete, means smaller elements can be used, lowering the quantity of material required, and therefore the embodied energy.

Materials created from recycled reversible materials, such as steel, include all the embodied energy from the scrap material used to produce new steel, in reality that means the embodied energy increases every time its recycled and reused.

And that means the real quantity of embodied energy in steel, and other products is infinitely higher than the energy use in production alone.



For more information about our embodied energy studies and

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date: 20-09-19