Course:PHYS100/Final Project: Argon-Filled Windows

Physics 100 Final Project: Argon-Filled Windows

Elliott Boake Sonja Dobbs Kelly Speck Flora Petersen Physics 100: Tutorial LJ1

Final Project Proposal'

Topic: We will investigate whether installing low emissivity double-paned argon-filled windows is a cost-effective way of conserving energy and reducing winter heating costs.

Problem Statement: We will compare three types of windows, single-pane, double-pane air-filled, and low emissivity double-paned argon-filled windows. We will calculate the cost to install each type of window in a house. We will also calculate the total energy required to heat a house with each type of window for one 150-day winter, and from this we will calculate the total cost involved in heating a house with each type of window for one 150-day winter. We will then apply these results to 20 winters, as the low-emissivity double-pane argon-filled window is ensured for 20 years. From these results, we can use the bases of single- and double- pane air-filled windows to compare the cost of installation of argon-filled windows to the amount of energy conserved and money saved over 20 years’ worth of heating bills.

Relevant Physics: We will employ the use of the physics of heat conduction to calculate the heat required to heat a house for one 150-day winter. We will use the equation for the rate of conduction of heat across a temperature difference to determine the amount of heat lost through each of the three types of windows.

Model and Assumptions:"" We assume there are 150 days in a Vancouver winter, as suggested in the Physics 100 course. We will model a basic house, including the amount of rooms and the amount of windows per room. We will assume heat loss through walls, the ceiling, and the floor is negligible to simplify our calculations. We will determine the average outside temperature on a winter day in Vancouver, and compare this to a desired indoor temperature of 20°C. We will also determine the average heating cost for a Vancouver home per kW, the average cost of installing each type of window in a house, and the conductivity of each type of window pane.

Rough Draft:

Assumptions:

150-day winter heat loss only through windows via conduction ignore heat transfer through wall indoor temperature of 20 degrees C outdoor temperature of 5 degrees C glass panes are 3mm wide

Research:

http://freegreenenergyalternatives.com/blog/uncategorized/double-glazing-insulated-glass-and-energy-efficiency/ 12mm gap between panes windows efficient for 20 years

Energy and environmental benefits from advanced double-glazing in EU buildings pdf, The European Association of Flat Glass Manufacturers, 2005 conductivity of windows: single = 4.7 W/m2*K double/air = 2.7 W/m2*K double/argon = 1.4 W/m2*K

http://oee.nrcan.gc.ca/publications/infosource/pub/home/Heating_and_Cooling_with_a_Heat_Pump_Section6.cfm?attr=4 heating cost per kWh in Vancouver = 4.98 cents

http://www.bbc.co.uk/weather/world/city_guides/results.shtml?tt=TT000950 average outdoor temperature in Vancouver in the winter = 5 degrees C

Model:

house with 4 rooms, 1 window in each room each room is 100cm x 70cm

Single paned window: L=3mm= 0.003m kglass = 0.96 (www.engineeringtoolbox.com)

Double paned window: Lglass = each 3mm L of air space = 2mm kglass = 0.96W/mk kair = 0.024 W/mk

Argon-filled double paned window: Lglass = 3mm each L of argon filled space = 2mm kglass = 0.96 W/mk kair = 0.67(%) * 0.024 = 0.016 W/mk

Calculations:

Area of each window: 100cm*70cm = 7000cm2 = 0.7m2

Conduction:

single pane: $Q/t=(k*A/L)*t$ = (0.96 W/mk) *(0.7m2)*(20C - 5C) / 0.003m = 3360W

double pane:

Formula $Q/t=(k*A/L)*t$ can't be used because we have two values for thermal conductivity constant k (air and glass). Therefore we imagine the entire window being entirely composed of glass, meaning we replace the middle air gap with glass and recalculate the constant k:

How thick glass is to conduct same heat as central 2mm air gap: Qglass/t = Qair/t kglass * A (Tin - Tout)/Tglass = kair * A * (Tin - Tout)/ Lair

Area and Temperature are the same in both therefore: kglass/Lglass = kair/Lair $Lglass=kglass/kair*Lair$ = 0.96 W/mk / 0.024 W/mk * 2mm = 80mm

Therefore we can replace the middle air gap with 80mm of glass. Total thickness of pane: L = 3mm + 3mm + 80mm = 86mm

$Q/t=(k*A/L)*t$ = 0.96W/mk * (15C) / 0.086m = 167.4 W

Argon-filled pane: $kargon*A(Tin-Tout)/Tglass=kargon*A*(Tin-Tout)/Lair$ = 0.96 W/mk / 0.016 W/mk * 2mm = 120mm

Total thickness of pane: L = 3mm + 3mm + 120mm = 126mm = 1.26m

$Q/t=(k*A/L)*t$ = 0.96W/mk * 15C / 1.26m = 11.4W

Cost:

Single: 3360W = 3.360kW * 3600h = 12096kWh 12096kWh * 4.98Cents/kWh = 60238 Cents = $602.38

Double: 167.4W = 1674kW * 3600h = 6026.4kWh 6026.4kWh + 4.98 Cents/kWh = 30011 Cents = $300.11

Argon-filled: 11.4W = 0.144kW * 3600h = 410.4kWh 410.4kWh * 4.98Cents/kWh = 2044 Cents = $20.44