Lesson Overview

Students will learn about heat transfer and the insulative materials we use in houses to limit heat transfer. Students will design model homes with different types of insulation and test which materials stop heat transfer the best. Students will calculate how their tested insulation choices will save money in heating fuel over time.

Target Grades: 6-12 / 6-8 / 9-12

Set Up Time: 1 hour

Class Time: 3 hours (over multiple class periods or one half day)

Lesson Resources

Objectives

1. Learn the calculations for insulation R-values and cost

2. Design an insulation assembly for a model house

3. Compare heating costs of different assemblies over winter.

Guiding question: How do different insulation materials effect how much heat is transferred through the walls of our houses?

Educational Standards

ALASKA CULTURAL STANDARDS: B3 & B4

ALASKA MATHEMATICS STANDARDS: 6.NS.3; 7.NS.3; 9-12.N-Q.1; 9-12S-ID.6

ALASKA SKILLS FOR A HEALTHY LIFE: D1, D2

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

ENERGY LITERACY CONCEPTS: 1.2, 1.7, 5.3. 6.8

NGSS: MS-PS3-3; HS-PS3-4

Lesson Preparation:
  • Read the Background section below
  • Build the Snug House assembly for each group
  • Prepare all other materials
  • Print the Snug House Student Worksheet (plus other worksheets for optional extension activity)
Gather Materials:
  • Snug House Student Worksheet 
  • Variety of insulation materials cut into 1 ft x 1 ft pieces
  • 1 “house” set up per 3-4 students (see Assembly Instructions for building the “house”)
  • 2 digital thermometers per “house”
  • 1 ruler per “house”
  • Calculators
  • Heat Loss Extension Activity student worksheet (optional extension)
  • 1 infrared thermometer per group (for extension activity only)

According to the Alaska Energy Authority’s 2012 End Use Study, the majority of energy consumed in residential buildings in Alaska is used for heating (80% in the Railbelt and Southeast Alaska and 72% in Bethel).  Significant energy and cost savings can be achieved through proper building design, such as efficient insulation. The Alaska Legislature has adopted an energy efficiency goal of 15% energy use reduction by 2020 and the U.S. Department of Energy has a specific target to make new and existing homes 40% more energy efficient by 2025 relative to 2010 (https://energy.gov/eere/buildings/downloads/multi-year-program-plan).

Heating is the single largest energy use for homes in Alaska. Homes need proper insulation as a barrier between the outside elements and a comfortable indoor living environment. Insulation essentially works by creating pockets to trap air. The R-value of the insulation is how well that air gets trapped and resistance of heat transfer (by conduction) through the material, around the air.

The different types of insulation that are typically used in Alaska include fiberglass, polyisocyanurate, expanded polystyrene, extruded polystyrene, and cellulose, all with differing R-values and costs. The R-value is measured per inch (width) and the price is measured per inch per square foot. In this activity, the insulation should be cut in 1 foot squares so that it fits in the box and that it makes calculating cost easy (just multiply by the width in inches). All of the insulation except cellulose is made out of state and shipped up. There is a state vendor in Wasilla that makes cellulose, and other materials, from recycled paper, especially newspaper. There is a fire retardant added to the material so that it is as safe to use as other insulation types. 

InsulationR-value (per inch)Price (per inch/ft2)
Fiberglass batt (FB)3.14$0.15
Expanded polystyrene (EPS)4.00$0.48
Extruded polystyrene (XPS)5.00$0.58
Polyisocyanurate (Poly)7.20$0.69
Cellulose3.70$0.06

Note: Although normally it is more scientific to use the metric system, the building science standard is to use Fahrenheit and inches, so this activity uses those units as well to be more accurate to real-life building science.

Conduction – The primary method of heat transfer through solid objects that are in contact with each other. Heat travels through a solid material across a thermal gradient.  

Convection – The primary method of transfer of heat through liquids and gases that are in contact with each other, in circulation. 

Radiation –  The way heat travels in a straight line through open space (not needing a solid, liquid, or gas) and heats anything solid in its path. This is the method of heat transfer from the sun.

Insulation – material used to prevent or interrupt the transfer of energy (including heat, electricity, or sound).

R-value – Thermal resistance, which is 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.

Fiberglass – A type of insulation that is made of thin strands of glass, typically used in batts.

Cellulose – A type of insulation that is usually loose and is blown-in. An Alaskan company makes cellulose from recycled newspaper.

Gear Up:
  • Option 1: Students brainstorm the different aspects to plan for when building the frame and insulation of a house. 
    • Why is insulation needed when building a house?
    • How can students determine how much insulation is needed?
  • Option 2: Students build the houses themselves as a part of the engagement. Refer to the Snug House Assembly Instructions.
Activity:

Students will be guided through new concepts and formulas with the Snug House Lab student worksheet. This worksheet can be done individually or in groups.

Day 1: 

  • Distribute the Snug House Student Worksheet.
  • Present the PowerPoint presentation to introduce (or review) concepts of heat loss and insulation. The answers to all of the blanks on the first page of the student worksheet are included in the presentation (underlined and bold).
  • Before you explain R-value, direct students to brainstorm in their groups the research question your class will be testing for: What insulation assembly will minimize heat loss from inside the snug house to the outside?
  • Students use available materials to create the insulation for their set up, using any combination that will fit in the box. This will be their hypothesis.
    • Tell them that their first insulation set-up is the research method they will use to test their hypothesis, based on their previous knowledge and the background information.
    • For the first test, they can only build up to 6” of insulation, simulating a 2”x6” stud common in Southcentral and older buildings in other areas of the state
    • Once all groups have assembled their insulation, set the timer for the amount of time you have available in the class to test the assembly – from 30 minutes to 1 hour. 
    • Students record a “0” reading, then plug in the lamp and take readings every 10 minutes for the “inside” and “outside” temperatures.
    • Between readings, explain R-value and have them calculate their total R-value and cost for their assembly. They then go through the questions on pages 4 & 5 that guide them through R-value recommendations for their area. 
    • As a class, review the answers and discuss why it’s important to have recommended R-values for different regions. 
    • If there is time, or for students who are working ahead, allow students to do the Web Energy Exercise linked at the bottom of page 4.
    • At the end of the test, students also calculate the temperature gradient between the “inside” and “outside” of their assembly. 

Day 2: 

  • Direct students to redesign their insulation assembly with these restrictions to simulate real-life situations:
    • Only use two types of materials
    • Meets the minimum recommended R-value for their region
  • They should also try for a set up that has one of these three options:
    • Increased R-value for the same cost OR
    • Reduced cost for the same R-value OR
    • Reduced cost AND increased R-value
  • Discuss that in engineering, there are always trade-offs: they will unlikely be able to build the cheapest insulation assembly AND have the best R-value.
  • This design represents their revised hypothesis, based on the results of the first trial. 
  • Set up the timer for the same amount of time as the first day.
  • In between readings, on the last page, students calculate how much their insulation would cost to heat in their region over a year. 
  • For more advanced students, you can look up heating degree days and/or cost of heating oil to determine a more accurate price for your community.
  • Have the students share the results with the class, such as in Google Sheets or as a mini-presentation. 
  • Encourage students to ask each other questions about their findings during the presentations. You can explain to them that in scientific research that process is called peer-review and is an important step in publishing research. 
  • Conclude the lesson by reviewing energy efficiency and the importance of insulating your house to save money and reduce impacts on the environment.
Extension:
  • Have students conduct the Snug House Heat Loss Extension Activitywith Infrared (IR) thermometers. The worksheet for this extension is included with the Snug House lesson materials.
    • In this activity, students will be able to test where the most heat loss is occurring in their assembly. Ask students to think what else they could do to reduce heat loss (i.e., caulk cracks, have more insulation on roof, etc). Students document their answers in the worksheet.
  • The Energy Efficient House Part 2 simulation activity is a possible follow up lesson, found at http://www.AKEnergySmart.org/.
    • In this lesson, students use a computer model to explore how choices made when designing a house will affect energy consumption, costs, and savings. 
  • Use an insulation savings calculator to determine how much money would be saved per year, such as can be found at this website: http://www.cellulose.org/HomeOwners/CalculateSavings.php
    • Students input square feet, heating degree days, and R values, then the website calculates the savings per year and in 10 years. 
    • There are preset costs of different energy sources, or students can research and input the prices in their communities. You can then use the cost of the insulation for the assemblies they built in class to calculate simple payback.
Evaluation:

Ask students to:

  • Work in groups to test multiple variables
  • Decide as a group which variables they would choose to minimize heat loss while staying affordable
  • Complete and submit the Snug House Student Worksheet