Floor Area: $2600$ sf $(1300$ sf each floor level$)$

Wall Area: $1050$ sf $($upper level$),500$ sf $($lower level$)$

Roof Area: $1300$ sf

Window Area: $300$ sf

Upper$-$level wall $($R$17)->$ U$-$value: $0\mathrm{.}060$ Btu$/$hr$$ft$2\backslash$deg F

Lower$-$level wall $($R$19)->$ U$-$value: $0\mathrm{.}053$ Btu$/$hr$$ft$2\backslash$deg F

Roof $($R$12)->$ U$-$value: $0\mathrm{.}080$ Btu$/$hr$$ft$2\backslash$deg F $($dark color$)$

Windows: wood, single glazed with $1/8$ in$.$ clear panes

The foundation wall $($R$-10)$ is insulated, and the slab is not insulated. The construction tightness of this building is considered $$loose$.$ The family keeps the thermostat at $68\backslash$deg F on winter nights, and at $75\backslash$deg F on summer days.

The upper floor of the house is air$-$conditioned, and the lower floor $$naturally$$ maintains

a temperature close to that because it is half underground, with little direct solar gain.

$1.$ Refer to Table B$\mathrm{.}1.$

a$.$ Design temperature for heat loss calculation?

b$.$ And $\backslash$Delta T$(\backslash$deg F$)?$

$2.$ U$-$value of the window? Refer to Table E$\mathrm{.}14.$

$3.$ Determine the total heat loss $($Q$)$ through the above$-$ground building envelope.

Q$($Btu$/$hr$)=$ U$($Btu$/$hr$$ft$2\backslash$deg F$)$ x A$($ft$2)$ x $\backslash$Delta T$(\backslash$deg F$)$

a$.$ Q through upper$-$level walls?

b$.$ Q through lower$-$level walls?

c$.$ Q through roof$/$ceiling assembly?

d$.$ Q through windows?

e$.$ Total Q$?$

$4.$ Determine the total heat loss $($Q$)$ through the below$-$grade walls and floor. The

ground temperature is $28\backslash$deg F$.$ The perimeter of basement wall is $100$ ft$.$ The depth

of below$-$grade floor is $7$ ft$.$ Refer to Table E$\mathrm{.}13.$

Q$($Btu$/$hr$)=$ U$($Btu$/$hr$$ft$2\backslash$deg F$)$ x A$($ft$2)$ x $\backslash$Delta T$(\backslash$deg F$)$

a$.$ Q through below$-$grade walls?

b$.$ Q through floor slab?

c$.$ Total Q$?$

$5.$ Determine the heat loss $($Q$)$ from infiltration through cracks in the building

envelope. This is an old residence; thus, no other fresh air source is provided.

The volume of the building is $16,000$ cubic feet. Refer to Table E$\mathrm{.}27.$

Hint: Q$($Btu$/$hr$)=1\mathrm{.}1($Btu$$min$/$ft$3$hr$\backslash$deg F$)$ x CFM $($ft$3/$min$)$ x $\backslash$Delta T$(\backslash$deg F$)$

CFM$($ft$3/$min$)=$ V$($ft$3)$ x ACH$($AC$/$hr$)$ x $1/60($hr$/$min$)$

Where V $=$ volume of building in cubic feet

ACH $=$ Air changes per hour

Q through infiltration?

$6.$ Total heat loss $($Q$)$ of this house?