Energy & Its Impact on Global Society

1. Energy & Its Impact on Global Society Jerome K. Williams, Ph.D. Saint Leo University Dept. Mathematics & Sciences

2. Chapter 5: Home Energy Conservation and Heat Transfer Control • Home Design Activity • Building Materials • Site Selection of Home • Energy Conservation Measures • Heating & Cooling Home

3. Home Design Activity • If money were not a concern, what would be the most effective design to heat and cool a home?

4. Home Design Activity • Since we live in the “real world”, what can one do to control heating and cooling costs? • Choice of home design • Retrofitting an older house • Energy efficient appliances • Addition of solar energy features

5. Home Design Activity • Ultimate Goal: Zero-Energy House (ZEH) • Idea is to make house livable on nearly no net commercial energy input • Run the meter “backwards” thereby having power company pay the homeowner money for unused energy

7. Building Materials • Choice of materials is important • Metals are good conductors of heat and electricity • Fiberglass or Styrofoam are insulators; these will slow down the flow of heat between objects. • Color of material does have impact on heat transfer by radiation

8. Building Materials • Increased insulation is one of easiest, most cost-effective means of reducing energy consumption • Can save up to 50% on heating & cooling bills • Rate Heat Flow= (Q/t) = (1/R) x A x ΔT • Tables 5.1 & 5.2

10. Building Materials • A measure of material’s resistance to heat flow is thermal resistance R, also called R-value • The higher the R value, the better the insulating properties of the material • For composite materials, add up all R values for mixture

11. Example Problem • Calculate the total heat transfer for 12 hours through an insulated window (two glass panes with an air gap of ¼ in.) that measures 4 ft. by 7 ft. when the outside temperature is 5 oF and the inside temperature is 65oF. • Answer 13,100 Btu

12. Building Materials • R values include effects of conduction and convection • Convection can be reduced by planting trees and shrubs near a house to reduce wind • Inside convection loss around windows can be reduced by using floor drapes and valence

14. Building Materials • Windows: important source of heat loss (35% of energy requirements for insulated home) • Solutions to Problem • Double Pane Windows (Required New Homes) • Plastic Storm Windows (Cheaper; Replace often) • Weather Stripping & Caulking (Easy; Cheap)

15. Building Materials • Windows: important source of heat loss (35% of energy requirements for insulated home) • Solutions to Problem • Double Pane Windows (Required New Homes) • Plastic Storm Windows (Cheaper; Replace often) • Weather Stripping & Caulking (Easy; Cheap)

16. Site Selection of Home • Location, Location, Location • Use Wind to cool in summer but not freeze in winter • Path of Sun: Solar energy panels face south to capture energy in winter

17. Heating & Cooling Home • Air Conditioning vs. Passive Cooling Systems • Heating Options • Gas Furnace • Heat Pump System • Electrical Resistance Heating System

18. Energy Conservation Measures • Home Energy Audit • http://energy.gov/public-services/homes/home-weatherization/home-energy-audits

19. Problems • 3, 5, 7, 8