BSCI 3101 - Applications in Building Science

Lab Assignment 4: Wall Design (worth 5%)

Due Date: Submit hard copy at the start of your next scheduled lab session, one submission per group (so you have one week)

Working in your Group House Design Project groups (you may want to exchange e-mail addresses so you can work together outside of class), you have been asked to help with the design of a building located in Sudbury, Ontario (H.D.D below 18 = 5400). The building permit was issued after December 31, 2017 so you are working in accordance to Chapter 3 of SB-12 of the OBC revision of the Ontario Building Code. This house is to be heated with electricity at a cost of $0.12/kW^.h. by means of an air source heat pump (ASHP). Design a wood frame wall assembly that will satisfy the code minimum nominal RSI and any

other relevant requirements and answer the following questions:

1. According to the code, what are the minimum nominal and effective RSI values required for the above grade walls? Min. Nominal RSI (1) 3.87 + 1.32 ci Max. U(3) 0.238 Min. Effective RSI(3) 4.21

1. Demonstrate by calculations that the minimum nominal RSI is met with the materials you have specified to satisfy the code (listing the k or c values for each and give thicknesses etc.). Remember, lumber only comes in fixed dimensions (2x4, 2x6 etc.) so for economy, stick to what is commonly available and associated insulation thicknesses (which also come in 0.5" increments of thickness).

1. Draw a horizontal cross-section sketch (plan view cut through wall) and an elevation sketch of the wall from the outside, with all relevant elements (vapour barrier, interior gypsum board, exterior sheathing etc.) showing, roughly to scale and all elements clearly dimensioned. You may sketch by hand or using software (but do not copy directly images from the CWC or other websites. Do your own.)

1. Calculate the effective RSI value of the assembly using the area-weighted-average method for any non-uniform layers and then the tabular method to get RSI-total. Include all material layers, including air films, and compare this "effective" R-value to the "nominal" R-value you stated in part 2a) and to the effective R-value specified in the OBC.

1. Demonstrate whether or not your assembly meets the OBC requirements in accordance to section 9.25.5.2 "Ratio of Outboard to Inboard Thermal Resistances". Reference any technical product data if/as needed.

1. If indoors is kept at 20C and 40% rh during January, while using -18^oC for an outdoor design temperature, calculate and plot the temperature profile through the clear wall section (no framing), clearly marking the dew point location for the inboard air. Comment on whether or not the wall can be considered "safe" or "durable" in terms of potential moisture accumulation due to leakage of indoor air into the wall under the above conditions.