A building with a composite wall structure with a surface area of $300$ m $2$ experiences $30C$ and $80\%RH$ on the outside and $20C$ and $40\%$ RH on the inside. The wall consists of a $20$ cm thick outer face brick $(k=15\frac{W}{m}K),$ a $5$ cm board of fiberglass insulation with $k=7\frac{W}{m}K,$ and a $1$ cm sheet of gypsum board with $k=5\frac{W}{m^2}.$K$).$

Determine

a$)$ Overall thermal resistance $R_{\text{t}\text{o}\text{t}\text{a}\text{l}}$ of the wall

b$)$ The overall heat transfer coefficient

c$)$ The heat load due to heat transmission

$(50$

points$)$