Lesson Overview

Students will model an energy efficient house using an Excel spreadsheet. Students will explore how choices made when designing a house will affect energy consumption, costs, and savings.

Target Grades: 6-12

Set Up Time: 30 minutes

Class Time: 1.5 hours

Lesson Resources

Objectives

1. Balance upfront investment costs with long-term benefits.

2. Design an energy efficient house using an Excel spreadsheet model.

3. Manipulate different variables to explore trade-offs between the costs and savings of investing in energy efficient buildings.

Guiding question: How can we use a computer model to calculate the energy consumption and financial future of a home?

Educational Standards

ALASKA CULTURAL STANDARDS: B3 & B4

ALASKA ENGLISH LANGUAGE ARTS:
Reading for Informational Text: 6-8 RST.KI.3; 6-8 RST.CS.4; 6-8 RST.IKI.7
Writing: 6-8 WSLST.RBPK.7; 6-8. WSLST.RW.10

ALASKA MATHEMATICS STANDARDS: 6.SP.5.b

ALASKA DIGITAL LITERACY STANDARDS: 6-12.EL.4; 6-12.ID.2; 6-12.ID.3; 6-12.CT.1-4

ENERGY LITERACY CONCEPTS: 1.2, 1.7, 5.3. 6.8

NGSS: MS-ETS1-4

Lesson Preparation:
  • Read the Background section below
  • Prepare computers and worksheets for students
Gather Materials:
  • Computers with Microsoft EXCEL
  • Modeling Your EE House.xlsx file
  • Modeling Your Energy Efficient House Guide
  • Modeling Your Energy Efficient House student worksheet

Building a house requires budgeting, prioritizing, and making tradeoffs.  Decisions regarding insulation and energy efficiency will impact the long term energy use of the building and its annual energy costs.

Significant energy and operating cost savings can be achieved through proper building design as well as use of energy efficient appliances and systems. However, incorporating energy efficient house design and appliances usually increases the cost of the initial investment.

Models provide simplified scenarios to use as learning tools to explore how choices and factors can impact outcomes. While the model presented is based on actual building costs, it is designed only for educational purposes and not analyses of actual buildings.

Climate Zone– A geographic classification based on climate. In the construction industry, the recommended minimum amount of insulation to use when building is dependent on the climate zones. Alaska is included in the national system that divides the United States into different climate zones. Alaska contains four climate zones: Zone 6 (Southeast), Zone 7 (Southcentral and Aleutians), Zone 8 (Interior, Southwestern, and Western), and Zone 9 (North Slope). 

British Thermal Unit (BTU) – A unit used to measure energy. It is the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit and it is equivalent to 1055 joules.  A BTU is approximately the amount of energy that one match stick gives off. 

Footprint of a House – The outline of the exterior walls of a house, i.e. what the foundation of the house supports. The footprint does not include external living areas such as porches or courtyards.  

Payback – The length of time that it takes to recover the cost of an investment.  For example, if an upgrade costs $100 but it reduces your cost by $50/year, the payback will be two years since two years of saving $50/year will be equal to the original investment. 

R-Value – A measure of how well a material insulates and resists heat transfer.  It is a term used in the construction industry to rate a building’s insulation in its roof, walls, and foundation. A high R-value indicates greater insulating effectiveness; the higher the R-Value, the better the building is able to retain heat inside or resist heat from outside. 

Regional Cost Factor – The cost of living varies greatly across Alaska due to energy and transportation costs.  The regional cost factor rates how expensive products are in different regions of the state. In Alaska, Anchorage is considered the standard, so an area with a regional cost factor of 3 indicates that, on average, the cost of living in that region is three times more expensive than Anchorage.

Thermal Envelope – The shell of the building that acts as a barrier to separate the interior of the house from the outside and limits unwanted heat or mass transfer between the interior of the building and the outside conditions. The thermal envelope includes the frame of the house, insulation, the vapor barrier, and siding.

U-Factor– A measure of how well a material conducts heat, usually used in reference to a building’s windows.  A material’s U Factor is the inverse of its R-value: U Factor = 1/R-value, so a high R-value is equivalent a low U Factor.

Gear Up:
  • This lesson is designed to follow the lesson Designing Your Energy Efficient House Part One: The Heat Loss Equation.
Activity:
  • Use the Designing Your Energy Efficient Home Guide, students will fill in their building choices in the Designing Your EE House Part 2 Spreadsheet Model Excel file worksheet on the computer.
  • They will then answer the questions on the Modeling Your Energy Efficient House student worksheet.
Extension:
  • A model is a simplification of a complex system, so it can be seen as a tool to explore relationships between different variables.  Because of this, it may not be as applicable for situations beyond the scenario described.  In this model, the largest footprint of a house is 1248 sq. ft.  The 2009 Alaska Housing Need Assessment reports that mean house size differs by region and ranges from 1,000 sq ft (Calista region) to 1850 sq ft (Cook Inlet region).  How well does this model represent the average household’s energy use for homes in different regions of Alaska?  How well does this model represent energy use in the students’ own homes? Have them measure or approximate the size of their houses’ footprint to compare.
  • Students can look at the AK Warm program available from the Alaska Housing Finance Corporation website at http://www.ahfc.us/reference/akwarm.cfm.  The AK Warm software is used by energy raters to determine a building’s energy rating. 
Evaluation:

Ask students to:

  • Complete and submit the student worksheet.