Project Purpose

This project analyzed the impact of shower usage on indoor environmental conditions and quantified the resulting HVAC cooling load and cost. The goal was to determine how temperature, humidity, and pressure changes in a confined bathroom environment translate into energy demand for restoring baseline conditions.

By combining experimental data collection with thermodynamic analysis, the project aimed to provide a realistic estimate of HVAC energy consumption and evaluate whether common assumptions about energy usage during daily activities (like showering) are accurate.

Technical Process

Data Acquistion & Experimental Setup

Built a custom environmental monitoring system using:
1. Arduino microcontroller
2. Thermistor (temperature)
3. Humiture sensor (relative humidity + temperature)
4. Barometric pressure sensor
Sensors recorded data before, during, and after 5-minute and 10-minute shower trials
Bathroom environment was isolated (HVAC off, vents sealed) to reduce external influence

Setup for measuring temperature, humidity, and pressure during shower operation

Software & Tools

Arduino (C/C++) → sensor data collection
Excel → data organization and visualization
Engineering Equation Solver (EES) → thermodynamic property calculation

Code Summary

Arduino script:
- Reads analog thermistor data and converts to temperature
- Interfaces with humidity and pressure sensors
- Outputs formatted serial data
Processing script:
- Captures serial data stream
- Writes structured dataset to CSV for analysis

Analytical Methodology

Calculated heat added to the air using:
- Mass of moist air (from volume and specific volume)
- Change in internal energy (from temperature, pressure, humidity)
Determined HVAC work using:
- Coefficient of Performance (COP ≈ 3)
Estimated monthly cost using:
- Local electricity rates and usage assumptions (60 showers/month)

Results

The experiment demonstrated a clear relationship between shower duration and HVAC energy demand:

5-minute shower:
- Heat added: 205.11 kJ
- HVAC work required: 68.37 kJ
- Estimated monthly cost: $0.11
10-minute shower:
- Heat added: 289.18 kJ
- HVAC work required: 96.39 kJ
- Estimated monthly cost: $0.15

Key Insights

Longer showers significantly increase humidity and thermal load
HVAC energy required to restore conditions is much lower than expected
Cooling cost contribution from showering is negligible compared to total energy bills
Sensor data showed strong agreement across multiple measurement methods, validating the experimental setup

Takeaway

The results demonstrated that HVAC cooling costs associated with showering are significantly lower than initially expected, with estimated monthly costs of $0.11–$0.15. This indicates that the majority of household energy consumption is likely driven by other appliances such as water heaters and kitchen appliances rather than short-term cooling loads.

Temperature, Humidity, and Pressure Change During 5-Minute Shower

Technical Report

Shower_Run_HVAC_Load_Report.pdf