Question

A wall in a building has a width of 15 m and a height of 3 m. It is made of several layers — a layer of motionless air with an R value of 0.12 K m2/ W, a 12.4 mm thick layer of gypsum board with a thermal conductivity of 0.17 W/m K, a layer of brick with an R value of 1.7 K m2/ W, and another layer of motionless air with an R value of 0.12 K m2/ W.

(a) If the temperature inside the building is 27.2◦C and the temperature outside is 33.1◦C, how much power will flow through the wall in steady state?

(b) How much power will flow if we add a layer of foam insulation with an R value of 27.0 K m2/ W?

Answer 1

PowER ELOW THROUG E ACH WALL LAYER OF A 7 STEADY STATE SAME 7D EGUAL A LOT AREA OF WALL SET EJEEN ST- DIFFERENCE TEMPREUR R EFF. OUT SIDE BuzLDINCa INSIDE REFF EFFECTIVE FLOW FLOW 17 RESISTANCE 70 RESESTANCE R+R REFF OF CAYER -o.12 k2 े R AIRI R BRICK O12 AIR 2 j LAXER OF THICKNESS AYPSUM K K THERMAL CONDUCTZVZTY OF LAYER t 2-x10m O07 Rarpsum ((50 यडभ ) ( अआन = २-२) ए Lo12+ +7+012 0-07)Km2 i5 x3)(311- 22.2 Or12 7 + 0-12+ 0-67 +27 1 b)P CN E