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Scenario
You are part of a design team for a small building contractor tasked with assessing a residential
house construction project, your focus will be to look at construction methods and materials.

Your client is an individual who is looking for a high level of sustainable technologies to be
incorporated in their project, to achieve low embodied energy, high levels of insulation and good
airtightness, energy efficiency, low maintenance and a long service period.

The project consists of detached house to be built on soft clay, which is classed as a high shrinkable
clay soil, the building is not expected to exceed 30kN/m. Although, soil type has been established,
please state your assumed local climate conditions as this will influence your assessment of
methods and materials.
Task
Your assessment will take the form of a technical report and will be aimed at a client with some
basic knowledge of standard construction methods. The technical report should contain an
introduction, some titled sections for discussion topics with illustrations, tables for comparison and
conclusions.
a. For each of the four primary elements (listed below), pick two methods of construction
(including the materials) that would be the most sustainable in the long term, compare and
contrast these and recommend one:
• Foundation type
• Structural ground floor
• Structural external walls
• Roof structure.
Note, there will be a number of construction methods that can be used for each element,
however, you need to look at and compare two methods which you deem to be the most
suitable and then choose one which you want to recommend.

For each element, focus on methods and materials that are appropriate for your country
(local climatic conditions). Clearly describe the technology, and provide justification for your
recommended choice, explaining how it satisfies key performance criteria and why it is best
suited to local circumstances.
b. Outline which building services system would give the best balance between energy
efficiency, running costs and carbon dioxide emissions. Your discussion should focus on
one specific item, from the following:
• Cooling and ventilation systems; or
• Space heating systems; or
• Hot water systems

Provide at least one illustration with annotation for each of the following five drawings
(sketches) of the report. These illustrations should be in the appropriate discussion topic of
your technical report and include (as a minimum):
• a composite sketch or suitable illustration (with annotations) of the foundation; and
• a composite sketch or suitable illustration (with annotations) of the ground floor with
footings and Damp Proof Course (DPC) and Damp Proof Membrane (DPM); and
• a composite sketch or suitable illustration (with annotations) of the exterior structural
wall; and
• a composite sketch or suitable illustration (with annotations) of the roof with eaves
(fascia and soffit) and wall plate detail; and
• a schematic diagram related to the building services outlined.
d. Provide a brief ‘Conclusions’ section that highlights the common themes you have used
throughout the technical report, linking these themes to each element discussed.

Sample Solution

Technical Report: Sustainable Construction Methods and Materials for Residential House

Introduction:

This report assesses construction methods and materials suitable for a sustainable, low-maintenance residential house to be built on soft clay with a maximum load of 30kN/m². The client prioritizes sustainable technologies for low embodied energy, high insulation, airtightness, and energy efficiency.

Local Climate Assumptions (temperate climate):

  • Mild winters with occasional freezing temperatures.
  • Warm summers with moderate humidity.
  • Moderate rainfall throughout the year.

a. Sustainable Construction Methods and Materials:

i. Foundation Type:

1. Pile Foundations:

  • Description: Precast concrete piles are driven into the soft clay until they reach a stable load-bearing stratum. A pile cap distributes the weight of the building across the piles.

  • Sustainability Considerations: High embodied energy in precast concrete piles. Requires specialist equipment for installation.

2. Engineer Designed Shallow Foundations:

  • Description: A reinforced concrete raft foundation spread across a wider area to distribute the building load on the clay.

  • Sustainability Considerations: Lower embodied energy compared to pile foundations. Requires careful engineering design to optimize concrete usage.

Recommendation: Engineer Designed Shallow Foundations are recommended. While concrete has embodied energy, careful design can minimize its use. This method avoids the high embodied energy and disruption of pile driving.

Illustration 1: Foundation Systems

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ii. Structural Ground Floor:

1. Suspended Timber Floor:

  • Description: Timber joists supported on brick or concrete walls with a subfloor and finished floor above.

  • Sustainability Considerations: Renewable timber resource, but requires treatment for durability.

2. Insulated Concrete Slab:

  • Description: A layer of concrete poured over a layer of insulation and a damp-proof membrane (DPM).

  • Sustainability Considerations: Concrete has high embodied energy, but the insulation layer improves thermal performance and reduces heating/cooling needs.

Recommendation: Insulated Concrete Slab is recommended. While concrete has embodied energy, the excellent thermal performance reduces long-term operational energy and carbon emissions.

Illustration 2: Ground Floor Construction

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iii. Structural External Walls:

1. Cavity Wall Construction:

  • Description: Two brick leaves separated by a cavity filled with insulation.

  • Sustainability Considerations: Brick production has embodied energy, but the cavity provides good insulation.

2. Timber Frame Construction with Cladding:

  • Description: Timber frame with insulation panels and external cladding like weatherboard or brick slips.

  • Sustainability Considerations: Renewable timber resource, offers good insulation properties with careful selection of insulation materials.

Recommendation: Timber Frame Construction with Cladding is recommended. Timber is a renewable resource, and the construction method allows for thicker insulation layers compared to cavity walls, leading to superior thermal performance.

Illustration 3: External Wall Construction

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iv. Roof Structure:

1. Traditional Trussed Rafters:

  • Description: Timber trusses support the roof covering and ceiling.

  • Sustainability Considerations: Renewable timber resource, but complex trusses can require more material.

2. Prefabricated Timber Roof Cassettes:

  • Description: Factory-made insulated panels combining roof structure, insulation, and an internal ceiling finish.

  • Sustainability Considerations: Efficient use of timber with good insulation properties due to factory-controlled manufacturing.

Recommendation: Prefabricated Timber Roof Cassettes are recommended. They offer excellent thermal performance, efficient use of materials due to prefabrication, and faster construction times.

Illustration 4: Roof Construction

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