Teacher Notes
Alignment to NGSS Performance Expectation
HS-PS3-4: Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics).
Dimensional Alignment
- Science & Engineering Practice (SEP): Planning and Carrying Out Investigations - Students plan and conduct investigations individually and collaboratively to produce data to serve as the basis for evidence.
- Disciplinary Core Idea (DCI): PS3.B Conservation of Energy and Energy Transfer - Uncontrolled systems always evolve toward more stable states—that is, toward more uniform energy distribution (e.g., objects hotter than their surrounding environment cool down).
- Crosscutting Concept (CCC): Systems and System Models - When investigating or describing a system, the boundaries and initial conditions of the system need to be defined and their inputs and outputs analyzed and described using models.
Evidence Statement Mapping
- Identifying the phenomenon to be investigated: The task asks students to describe how changing insulation and HVAC elements affects thermal energy loss and the time taken to reach a stable internal temperature in a historic home.
- Identifying the evidence to answer this question: Students collect data on indoor temperature, heat loss (BTU/hr), and HVAC input to show the transfer of thermal energy between the house interior and the exterior environment.
- Planning for the investigation: Students must develop a testing matrix considering the constraints (budget, historical preservation) and available options for wall and attic insulation, plus HVAC systems, tracking energy transfer inputs and outputs.
- Collecting the data: Students record heat loss and indoor temperature across multiple design variations, including the initial 1874 configuration and modern retrofits.
Retrofitting the Mark Twain House: A Thermodynamics Challenge
Part 1: Engage (Anchoring Phenomenon)
The Mark Twain House, built in Hartford, CT in 1874, is an 11,500 square-foot Victorian Gothic masterpiece. With its massive uninsulated brick walls and steep roofs, keeping it warm during a harsh New England winter required a massive coal-fired boiler. Today, maintaining the house at a comfortable 68°F (20°C) is an enormous thermodynamic and financial challenge.
Your task is to apply modern thermodynamics and retrofitting techniques to minimize thermal energy loss while preserving the original historical architecture (e.g., you cannot destroy the original stenciled walls or exterior brick facade).
Discuss: Why does a large historic house lose heat faster than a modern home? What boundaries define this thermodynamic system?
Part 2: Explore (Simulation Investigation)
Access the simulation: Retrofitting the Mark Twain House. The simulator models the thermodynamic transfer of energy between the house and the environment.
Procedure:
- Establish Baseline (1874 Conditions):
- Set Wall Insulation to
None (Original 1874 Lath & Plaster). - Set Attic Insulation to
None (Original 1874). - Set HVAC System to
Original Coal Boiler (60% Eff). - Set Outdoor Temp to
20°F. - Click Run Simulation. Record the Heat Loss (BTU/hr), HVAC Input, and whether the Indoor Temp can reach 68.0°F.
- Set Wall Insulation to
- Test Individual Variables: Click Reset. Change only ONE variable at a time (e.g., upgrade only the attic to Fiberglass). Run the simulation and record the impact on Heat Loss.
- Develop an Optimal Retrofit Plan: Plan and conduct an investigation to find the best combination of upgrades.
- Constraints: Your total budget is $150,000. You must not trigger a Historical Constraint Violation (which happens if you choose “Interior Demolition/Batt” or “Exterior Rigid Foam”).
- Goal: Achieve the lowest possible Heat Loss (BTU/hr) while maintaining 68°F indoors and staying under budget without damaging the house.
Data Collection Table
| Run | Wall Insulation | Attic Insulation | HVAC System | Outdoor Temp (°F) | Cost ($) | Heat Loss (BTU/hr) | HVAC Input (BTU/hr) | Indoor Temp (°F) | Historical Violation? |
|---|---|---|---|---|---|---|---|---|---|
| 1 (Baseline) | None | None | Coal Boiler | 20 | $0 | No | |||
| 2 | 20 | ||||||||
| 3 | 20 | ||||||||
| 4 (Optimal) | 20 |
Part 3: Explain (Sensemaking)
Using your data from the simulation, answer the following questions:
- System Boundaries: Define the system boundaries in this simulation. What are the major paths for thermal energy leaving the system?
- Energy Transfer: According to the Second Law of Thermodynamics, thermal energy flows from a warmer area to a cooler area until a more uniform distribution is reached. How does the choice of wall insulation change the rate of this energy transfer? Provide specific quantitative evidence from your data table.
- Efficiency: Compare the Original Coal Boiler with the Geothermal Heat Pump. Explain how upgrading the HVAC system addresses heat loss differently than upgrading the insulation.
Part 4: Elaborate / Evaluate (Argumentation & Modeling)
You have been hired by the Mark Twain House Museum board.
Draft a Scientific Recommendation: Write a formal recommendation detailing your optimal retrofit plan.
- Claim: State your chosen combination of Wall Insulation, Attic Insulation, and HVAC system.
- Evidence: Provide your simulation data showing the reduction in Heat Loss (BTU/hr) and total budget spent.
- Reasoning: Use the principles of thermal energy transfer (PS3.B) to explain why your plan successfully limits thermal energy loss compared to the 1874 baseline, and confirm that your plan respects the initial condition constraints (historical preservation and budget).