Photo AI
Designing for airtightness presents one of the most challenging aspects of contemporary house design - Leaving Cert Construction Studies - Question 9 - 2012
Question 9
Designing for airtightness presents one of the most challenging aspects of contemporary house design. (a) Discuss in detail the importance of careful design detaili... show full transcript
Worked Solution & Example Answer:Designing for airtightness presents one of the most challenging aspects of contemporary house design - Leaving Cert Construction Studies - Question 9 - 2012
Step 1
Discuss in detail the importance of careful design detailing in improving the airtightness performance of a dwelling house.
Answer
Careful design detailing is critical for improving the airtightness of a dwelling house for several reasons:
-
Sealing and Ventilation: Proper sealing around the internal fabric of the external envelope helps eliminate drafts. Continuous airtight seals ensure that air does not escape or enter undesirably, which is crucial for maintaining energy efficiency.
-
Impact on Performance: Details such as the correct positioning of membranes can drastically improve the air barrier performance. For instance, a failure in sealing can reduce the performance of the membrane by up to 1600 times.
-
Reduction of Moisture and Control: Effective design prevents issues related to moisture ingress, which can compromise insulation properties and lead to structural damage.
-
Skilled Installation: Design must account for the installation skill and propagation of materials, as improper installation can create vulnerability points for air leaks.
-
Proprietary Products: Utilizing specially designed tools and materials helps ensure airtightness, as they are manufactured to prevent air leaks effectively.
-
Testing: Post-construction air blower tests can verify the airtightness achieved, allowing for adjustments and improvements where necessary.
Step 2
Select any three locations from those circled on the sketch and show, using notes and freehand sketches, the typical design detailing which will prevent air leakage at each of the locations selected.
Answer
-
Ground Floor:
- Use airtight membranes and butyl sealing tape at the joints between the walls and floor to prevent any air flow. Ensure all mortar joints in the external wall are carefully pointed to maintain the barrier.
-
Window Cill:
- Install an air continuity barrier to damp proof the membrane at the window sill. All joints here must be properly sealed using tape and mastic sealant to prevent drafts from entering.
-
Light Fittings:
- Cables passing through should be insulated and sealed, using air tight grommets to ensure they align with the continuity barrier. Avoid recessing light fittings into the ceiling, as this can create air leakage paths. Use service cavities for electrical wiring where possible.
Step 3
Discuss the advantages of including a service cavity in an external wall of timber frame construction, as shown in the accompanying sketch.
Answer
Including a service cavity in an external wall of timber frame construction offers the following advantages:
-
Improved Thermal Performance: The service cavity contributes additional insulation, which enhances the overall thermal resistance of the wall, helping to reduce energy consumption.
-
Acoustic Insulation: It provides better sound insulation, which improves the living environment inside the dwelling by reducing external noise.
-
Easier Access for Services: The cavity allows for easier installation and maintenance of electrical and plumbing services without compromising the air barrier, ensuring that air leakage is minimized.
-
Airtightness: The design helps in achieving improved airtightness by creating distinct boundaries between conditioned and non-conditioned spaces, which is essential for energy efficiency.