Comparison of Embodied Energy Content in a Sample Conventional House and a Timber Frame House with Straw Insulation

Most of us are aware that fossil fuel reserves are not unlimited and will sooner or later be depleted; the question that remains open is only when this will happen. Scientists working in climatology are convinced that carbon dioxide emissions associated with the combustion of fossil fuels are the main reason for the occurrence of climate change and rising temperatures. The author of the diploma thesis compared the carbon dioxide emissions of a sample conventional house and a timber frame house with straw insulation. She demonstrated that the use of local and natural building materials significantly reduces the amount of carbon dioxide emissions. The comparison of embodied grey energy in different building materials shows considerable deviations between natural and artificial building materials.

Problem

Most of us are aware that fossil fuel reserves are not unlimited and will sooner or later be depleted; the question that remains open is only when this will happen. Scientists working in climatology are convinced that carbon dioxide emissions associated with the combustion of fossil fuels are the main reason for the occurrence of climate change and rising temperatures. Now it is up to the author; measures need to be defined that will contribute to reducing carbon dioxide emissions.

In the construction industry, we can do a great deal ourselves, especially in new builds, by choosing the right and energy-efficient building materials and making sensible choices regarding heating options. However, in order to assess a building from an ecological perspective, we must add up all the energy costs required for its construction, operation and removal. It is well known that building or renovating a property is a major financial undertaking.

If we decide to build or renovate a property, financial subsidies granted by the Eco Fund for the correct and efficient choice of materials are of great financial assistance to us. With their help, we select materials that are sufficiently energy-efficient. With proper installation, we can make a positive contribution to caring for a clean environment.

Today, houses are being built where energy consumption for construction and operation is so low that the buildings have a positive energy balance. If we build energy-inefficient buildings in contrast to energy-efficient ones, this has negative consequences for energy consumption and environmental burden in the future, due to large carbon dioxide emissions.

Solution and Method

The author of the diploma thesis compared the carbon dioxide emissions of a sample conventional house and a timber frame house with straw insulation.

Results

She demonstrated that the use of local and natural building materials significantly reduces the amount of carbon dioxide emissions. The comparison of embodied grey energy in different building materials shows considerable deviations between natural and artificial building materials. As the first hypothesis, she posed the question of whether a timber frame house insulated with straw insulation really produces fewer carbon dioxide emissions than a conventional sample house.

She accepted this statement with calculations and tables, as the values of embodied grey energy are considerably lower for the timber frame house than for the sample conventional house. The difference is in all three building elements. The external wall of the conventional frame house contains 289 MJ/kg of embodied energy, whilst the external wall of the timber frame house with straw insulation contains 134 MJ/kg.

A greater difference is observed in the roof and floor construction. The floor foundation slab of the conventional sample house contains 1789 MJ/kg of embodied energy, whilst the floor construction of the timber frame house with straw insulation contains only 102.6 MJ/kg. The same applies to the roof construction; for the sample conventional house, the value of embodied energy is 1393.2 MJ/kg, whilst in contrast, the roof construction of the timber frame house with straw insulation contains only 115.8 MJ/kg.

In total, the embodied grey energy values for the timber frame house are lower by 3078.8 MJ/kg. This means that a house built with timber and straw produces 3078.8 MJ less grey energy than a conventionally built house. The lower values of grey energy and carbon dioxide emissions for natural materials (timber and straw) are mainly due to the facts that these are local products, that they do not require much processing (timber needs to be sawn and dried; if it is technically dried, the carbon dioxide emission is slightly higher, whilst straw requires no treatment at all), and that the transport route from production or processing to installation is short.

The same also applies to the statement that artificial insulation materials require more production energy than natural ones. She also demonstrated this statement in tables and accepted the hypothesis, as the PEI (primary energy as the sum of primary energy from renewable and non-renewable sources) required for the production of natural materials is lower than the primary energy required for the production of artificial materials (shown in more detail in Table 6). The author of the diploma thesis demonstrated that the correct choice of building materials has a positive impact on the environment, as only in this way do we contribute to lower carbon dioxide emissions and a healthier environment for their lives.