Assessing a residential house construction project
Sustainable Construction Methods for Residential House: A Technical Report
Introduction:
This report outlines sustainable construction methods and materials suitable for a detached house built on soft clay with a maximum load of 30kN/m². The client prioritizes low embodied energy, high insulation, airtightness, energy efficiency, low maintenance, and a long lifespan. Local climatic conditions are assumed to be [insert details - temperate, hot & humid, etc.].
Foundation Type:
- Slab Foundation: A concrete slab directly cast on a prepared, reinforced sub-grade.
- Engineered Pile Foundation: Driven piles transfer building weight to a lower, stable soil layer.
Comparison:
| Feature | Slab Foundation | Engineered Pile Foundation |
|---|---|---|
| Sustainability | High embodied energy in concrete | Lower embodied energy in piles, minimal excavation |
| Suitability for Clay | Not ideal for shrinkable clay, prone to cracking | Suitable for unstable soils, minimizes settlement risk |
| Cost | Generally lower initial cost | Higher initial cost |
Recommendation: Engineered Pile Foundation. While the initial cost is higher, it offers superior stability on shrinkable clay, reducing the risk of cracking and ensuring long-term performance.
Illustration:
- A sketch showing a side-by-side comparison of a slab foundation (concrete slab on sub-grade) and an engineered pile foundation (piles driven into stable soil layer).
Structural Ground Floor:
- Suspended Timber Floor: Timber joists supported on pre-cast concrete beams or timber walls.
- Insulated Concrete Floor (ICF): Pre-cast hollow concrete units with integrated insulation filled with concrete.
Comparison:
| Feature | Suspended Timber Floor | Insulated Concrete Floor (ICF) |
|---|---|---|
| Sustainability | Renewable timber resource, good thermal insulation | High embodied energy in concrete, excellent thermal insulation |
| Suitability for Clay | Requires stable sub-floor to prevent joist deflection | Less susceptible to movement on clay due to rigid structure |
| Airtightness | More challenging to achieve airtightness | Excellent inherent airtightness |
Recommendation: Insulated Concrete Floor (ICF). While ICF has higher embodied energy, its superior thermal insulation, airtightness, and suitability for clay soils make it a better long-term choice.
Illustration:
- A sketch comparing a suspended timber floor (showing joists, beams, and subfloor) with an ICF floor (showing pre-cast units filled with concrete).
Structural External Walls:
- Timber Frame Construction: Timber studs with insulation and cladding materials.
- Straw Bale Construction: Compressed straw bales with internal and external render finishes.
Comparison:
| Feature | Timber Frame Construction | Straw Bale Construction |
|---|---|---|
| Sustainability | Renewable timber resource, good insulation | Excellent thermal insulation, low embodied energy |
| Suitability for Climate | Can be adapted to various climates | Particularly suited to moderate climates |
| Durability | Requires proper moisture management | Proper detailing crucial for long-term durability |
Recommendation: Straw Bale Construction. Assuming a moderate climate, straw bale offers exceptional thermal insulation, low embodied energy, and good structural performance with proper detailing.
Illustration:
- A sketch comparing a timber frame wall (showing studs, insulation, and cladding) with a straw bale wall (showing bales, internal render, and external render).
Roof Structure:
- Timber Truss Roof: Pre-fabricated triangular trusses supporting roof deck and coverings.
- Light Gauge Steel Frame with Rafters: Cold-formed steel sections forming a lightweight frame with timber rafters.
Comparison:
| Feature | Timber Truss Roof | Light Gauge Steel Frame with Rafters |
|---|---|---|
| Sustainability | Renewable timber resource | Steel is recyclable, potentially lower embodied energy |
| Span Capabilities | Can handle larger spans | Limited span capabilities compared to trusses |
| Fire Resistance | Requires additional fireproofing measures | Steel offers inherent fire resistance |
Recommendation: Timber Truss Roof. While steel offers recyclability, timber trusses are more suitable for larger spans commonly found in detached houses. Fireproofing considerations can be addressed during construction.
Illustration:
- A sketch comparing a timber truss roof (showing trusses, decking, and coverings) with a light gauge steel frame with rafters (showing steel sections, rafters, decking, and coverings).
Building Services System: Space Heating
A highly efficient Air Source Heat Pump (ASHP) system is recommended for space heating. ASHPs extract heat from the ambient air and transfer it to the building interior, offering excellent energy efficiency and lower running costs compared to traditional gas boilers.
Illustration:
- A schematic diagram of an ASHP system showing the outdoor unit, indoor unit, hot water storage tank (if applicable), and distribution system (hydronic or air ducts).
Conclusion:
This report explores