Wall Analysis $(30$ marks$)$

a$.$ Complete a thermal and vapour analysis spreadsheet for the following rainscreen wall assembly $(12$ marks$),$ a blank spreadsheet is provided on the Learning Hub. Watch the units. RSI $($Thermal Resistance$)$ values below are in metric $($SI$)$ units.

Exterior $(0\backslash$deg C$,$ and $80\%$ RH $$ Average Wintertime conditions$)$

$->6$mm$,$ Cementitious Board $($RSI$-0\mathrm{.}025,$ M$=3000$ ng$/$Pa s m$2$ due to ventilation$)$

$->19$mm$,$ Ventilated Airspace $($RSI$-0\mathrm{.}18,$ M$=50,000$ ng$/$Pa s m$2)$

$->50$ mm$,1$ Semi$-$Rigid Mineral Fiber Insulation

$->$ Vapour permeable self$-$adhered membrane

$->12\mathrm{.}7$mm$,(1)/(2)$ Plywood Sheathing $($near ~$70\%$ RH$)$

$->140$mm$,5(1)/(2)$ fiberglass batt insulation $($RSI$-3\mathrm{.}87)$

$->12\mathrm{.}7$mm$,(1)/(2)$ gypsum drywall

$->$ Latex Paint

Interior $(21\backslash$deg C and $50\%$ RH $$ Wintertime Indoor Conditions, High RH$)$

b$.$ Sketch the wall assembly and neatly sketch the thermal gradient $($i$.$e$.$ temperatures at each material interface, on a graph$)$ through the wall assembly. $(2$ marks$)$

c$.$ What is the R$,$ RSI, USI, and U values for this wall assembly? $(2$ marks$)$

d$.$ If you were to include the thermal bridging impact of wood framing occupying $25\%$ of the wall area, what would the effective R$-$value, RSI, USI, and U$-$imperial be$?$ See the formula on the last page. $(2$ marks$)$

e$.$ What is the $\%$ reduction in R$-$value and $\%$ increase in U$-$value when considering the framing? $(2$ marks$)$

f$.$ What material$($s$)$ in this wall assembly control vapour diffusion the most? $(2$ marks$)$

g$.$ Using the answer from $2$a$,$ what happens if you look at wintertime design conditions of $-7\backslash$deg C and $85\%$ RH for Vancouver? Where does condensation potentially occur? Does this short duration matter? $(2$ marks$)$

h$.$ Using the answer from $2$a and wintertime design conditions, would your recommendation for a vapour barrier change $($i$.$e$.$ would you add, remove, move, and$/$or change the vapour barrier$)$ if you were to remove the semi$-$rigid mineral wool from the assembly $($e$.$g$.$ no exterior insulation$)?$ What material would you suggest adding as a vapour retarder in the wall in this case? $(2$ marks$)$

i$.$ Using the answer from $2$a and wintertime design conditions, what happens if you were to replace the exterior mineral wool insulation with XPS insulation? How could you make this wall work? What are the risks of this recommendation? $(2$ marks$)$

j$.$ Using the answer from $2$a$,$ would your recommendation for a vapour$-$barrier change $($i$.$e$.$ would you add, remove, move, and$/$or change the vapour barrier$)$ if the design wintertime conditions were $-33\backslash$deg C and $90\%$ RH$,$ representing a building in Alberta? $(2$ marks$)$