lesson 7 review

# lesson 7 review - 1 The time it takes to recover the...

This preview shows pages 1–3. Sign up to view the full content.

1. The time it takes to recover the additional cost through energy savings is called C ) Pay Back Period Payback period is the time taken to recover the additional cost through savings. 2. How many degrees the mean temperature fell below 65ºF for the day is indicated by C ) HDD The HDD indicates how many degrees the mean temperature fell below 65ºF for the day. 3. Home heating is the single highest energy expense for a household. A ) TRUE Home heating is the single highest energy expense for a household 4. After a house is built, the easiest place to insulate a house is/are B ) Attic Attic is easiest place to insulate a house after it is built. 5. This mechanism does not need any medium (molecules or atoms) to transfer heat C ) Radiation Radiation is transfer of heat through electromagnetic radiation. In gases, liquids, and solids, energy is transferred by the molecules with or without their physical movement (convection or conduction). 6. Average cost of electricity in the US is B ) \$90/MWh In the US, electricity costs 9 cents per kWh 7. In state college the average temperature outside during the month of January was 30 degrees F. Calculate the HDD for the month of January. D ) 1085 degree days HDD = (65 - 30) * 31 = 1085 degree days 8. How many degree days are accumulated in a seven day period where the average temperature outside is 30 degrees Fahrenheit D ) 245 HDD = (65 - 30) * 7 = 245 degree days 9. Most of the households in the US use the following fuel for home heating A ) Natural Gas In the US, natural gas is the most commonly used household heating fuel. 10. Natural gas is sold in the US at \$1.14 per CCF. What is the cost of per MMBTU? Recall that 1 MCF = 1,000 Cu. Ft and has 1,000,000 BTU and 1CCF = 100 Cu. Ft and has 100,000 BTU. A ) 11.4 \$/MMBTU 1 CCF has 100,000 BTU 10 CCF has 1,000,000 BTU = 1 MMBTU Cost per MMBTU = 1.14 *10 = \$11.4 per MMBTU 11. Oil is sold in a particular region at \$1.8/gal. The heating value 139000 BTU/gal. What is the cost per MMBTU? B ) 12.95 \$/MMBTU Cost per MMBTU = 1.8 / 139,000 * 1000000 = \$12.949 per MMBTU 12. Natural materials like stone and bricks are not good insulation materials, A ) TRUE Natural materials like stone and bricks are not good insulation materials. 13. Heat is lost through walls, windows and roof of a house. The primary mechanism by which the heat is lost through the wall is B ) Conduction Heat is lost through solids by a mechanism called conduction.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
14. Of the following sources, where does the most heat loss occurs for a typical home? B ) Cracks in walls, windows and doors Cracks in walls, windows and doors are the places through which most of the heat loss occurs in a typical house 15. The R-value of a composite wall is calculated by A ) adding the R-values of all layers The R-value of a composite wall is calculated by adding the effective R-values of each of the layers of the wall. 16.
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 03/30/2008 for the course EGEE 102 taught by Professor Pisupati,sarmave during the Spring '07 term at Penn State.

### Page1 / 6

lesson 7 review - 1 The time it takes to recover the...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online