Reference no: EM132440379

BLDC 3050 - Building Envelope Performance - British Columbia Institute of Technology

Your client is building a high-end energy efficient home on the ocean in West Vancouver, BC. He has retained you to design and detail selected building enclosure assemblies and details. You have also been asked to perform a design heat-loss calculation to assist the mechanical engineer with the sizing of the heating system.

The standards for this project are above the minimum BC Building Code requirements in order to meet the client's energy efficiency requirements. The following minimum thermal and material specifications apply and serve as targets for your design:
• Walls, Above Grade: R-25 effective
• Walls, Below Grade: R-20 effective (use above grade values if sloped site)
• Slab on Grade: R-15 insulation, full slab coverage
• Suspended Floors (i.e. at overhanging wall), R-30 effective
• Attic Roofs: R-50 effective
• Sloped Cathedral Roofs: R-30 effective
• Roof Decks: R-30 effective
• Windows: R-5.0 (U-0.20) (Triple glazing, two low-e coatings, argon fill, non¬conductive frames). Selection covered in Part 2.
• Overall House Airtightness of less than 2 ACHSO (average 0.30 ACH at natural stack pressures)
The house claddings consist of standard cement stucco (7(r) and cultured stone veneer (1 IV). The roofing consists of a standing seam zinc metal roof. The decks will be concrete pavers as denoted on the drawings.

PART 1: Assembly Design and Basic Detailing

Using the provided 11x17 architectural drawings; design and draw the selected building enclosure assemblies and section detail for the following areas of the house. Include the critical barriers, materials, assembly analysis spreadsheet write up and calculations for R-value (or reference) as well as a discussion of each detail. Indicate the critical barriers and materials on each of the drawings.
1. Above Grade Wall Assembly
2. Below Grade Wall Assembly
3. Metal Roof Sloped Roof Assembly
4. Roof Deck Assembly
5. Below Grade Floor Slab Assembly
6. Detailed Building Enclosure Section from Below Grade Floor to Roof Including Window and Floor Interfaces. Ensure the window details are for you chosen window frame selected in Part 2.

You will determine how to conceptually attach the cladding and roofing to the structure using standard industry practices with your chosen assemblies. Include this in your discussion and with the appropriate assemblies.

You will find that the architectural drawings are incomplete, and it is up to you to determine where the insulation should be best placed and what product it is, and what materials would be required for air, vapour, moisture flow control in each assembly. Use what you have learned in class, plus the additional course material. Use appropriate design tools (i.e. vapour diffusion spreadsheet or other reference material and textbooks) to assist in the design of your assemblies and details. You will be marked on suitability of your design to meet the client needs (project specification) and climate.

PART 2: Window Selection

Windows for the house are to be selected by you from a local BC supplier to meet the minimum thermal performance criteria of R-5.0 (U-0.20).

List the manufacturer and summarized the relevant information for your selected window including U-value, SHGC and any other criteria you might find useful.

For the selected windows, you will need to evaluate the window frame design on the 9-point scale covered during the window class and Section 5.9 of the course textbook. To do this, draw a separate 1:1 scale sketch through the window sill profile and evaluate the following 9 criteria directly on the drawing.

Use your chosen window profile in the detailing of the assemblies.
1. Continuity of water shedding surface (WSS)
2. Continuity of water resistive barrier (WRB)
3. Vertical or sloped water shedding surface
4. Use of continuous compression gaskets for operable vents
5. Use of continuous compression gaskets or shimmed tape at glazing stops
6. Unobstructed drainage path within window between WSS and WRB
7. Capillary break between WSS and WRB
8. Continuous air barrier
9. Durable materials at frame joints

PART 3: Heat Loss Calculation

To perform a preliminary heat-loss calculation you will need to determine the overall effective U-value (and R-value) for the house to size the mechanical heating system (Hint see 4.11 of Chapter 4 of course textbook). You will need to estimate the insulated enclosure area and volume for the house from the drawings. Hint: This can be approximate, so do not spend too long performing the area take-offs. Be careful with units and perform calculations in metric units (areas in square meters and RSI/USI values).

Perform the heat loss calculation using the January Wintertime Design Temperature for West Vancouver of -9°C for the above grade components. Below grade heat losses are more complicated, but here assume a ground temperature of +5°C for assemblies in contact with ground.

• Total Heat Loss at design temperature = Conductive (Above +Below Grade) + Convective Heat Losses

• Conductive Heat Losses: Q = U.A.ΔT (Where: Q = heat loss in W, U = U-value in W/m².K, A = Area in m², ΔT = temperature difference in °C, separately for above and below grade)

• Air Leakage Heat Losses: Q = 0.3.n.V.ΔT (Where: Q = heat loss in W, n = number of air changes per hour at average conditions/pressures, V = Volume of house in m³, ΔT = temperature difference in °C)