Tiny House Experiments SMC

Teach principles of a passive house using a small tiny house measuring 0.4m square

Teaching the principles of a Passive House using a small model tiny house is a creative and practical way to help students or individuals understand the key concepts of passive design. While a tiny house model measuring only 40 cm square is extremely small, it can still serve as an effective educational tool. Here's how you can approach it:

• Focus on Key Principles: Given the limited space of the model, concentrate on a few fundamental principles of Passive House design. These typically include:
  • Superior Insulation: Show how high-quality insulation materials can be used in walls, floors, and roofs to minimize heat loss.
  • Airtightness: Demonstrate how to create an airtight building envelope, emphasizing the importance of sealing gaps and using airtight materials.
  • High-Performance Windows: Highlight the role of energy-efficient windows with multiple glazing layers and low U-values in preventing heat loss.
  • Ventilation: Explain the need for a heat recovery ventilation system to ensure a continuous supply of fresh air while recovering heat from exhaust air.
  • Passive Solar Design: Illustrate how to maximize solar gain through south-facing windows and shading in summer.
• Miniature Model: Create a detailed miniature model of the tiny house using materials like foam board, cardboard, or even a 3D-printed model if available. Ensure that it accurately represents a Passive House with adequate insulation and airtightness.
• Interactive Elements: Incorporate interactive elements such as removable walls or sections that allow you to reveal the inner workings of the building, like insulation and airtight layers.
• Digital Simulations: If possible, run digital simulations of the tiny house model using software that shows temperature distribution and energy flow to help visualize the passive design in action.
• Hands-On Workshops: Organize workshops where participants can add or modify insulation and airtightness components to see how these changes affect the model's energy efficiency.
• Data Logging: Use temperature and humidity data loggers inside the model to track the effectiveness of passive design strategies and observe real-time changes.
• Comparison to Standard House: Provide a side-by-side comparison with a standard house model to illustrate the differences in energy consumption and comfort between passive and non-passive designs.
• Discussion and Analysis: Encourage discussions about the importance of Passive House principles for energy efficiency, comfort, and sustainability. Discuss how these principles can be applied in real-life housing projects.
• Documentation: Document the entire process with photos, videos, and charts to create a visual record of the educational project.

By using this miniature model, you can effectively demonstrate the principles of a Passive House, even in a confined space. This hands-on and visual approach can be a powerful teaching tool for individuals of all ages interested in sustainable architecture and design.

Insulation

• Tiny House 8 with R4 Insulation

• Tiny House 9 NO Insulation

Thermal Mass

• Thermal mass is added to the Tiny House to stablise temperatures inside the Tiny House.
• On hot days, thermal mass takes a long time to heat up, keeping the inside of a house cooler.
• Likewise, thermal mass holds warmth which keeps a house warmer on the inside on cold days.
• Note that thermal mass does gain and lose heat, but this takes a long time.
• In this experiment we are adding thermal mass to the interior of an insulated Tiny House to demonstrate the temperature stability effect.

Experimental conditions

• Tiny Houses 0.4m square.
• R4 polyester insulation in both houses
• 2L Coke bottle used as Thermal Mass in one house.

2L Coke bottle acting as Thermal Mass. Temperature sensor taped directly to thermal mass

Temperature sensor measuring external temperature placed outside insulation. Temperature sensor to measure temperature of thermal mass placed within insulation jacket

Tiny House on left with R4 insulation. No thermal mass. Tiny House on right with 2L water bottle thermal mass and R4 insulation

Freeboard IO Dashboard showing the monitoring of both Tiny Houses to monitor the effects of Thermal Mass.

Results using Thermal Mass

• Thermal properties of the Tiny House with R4 insulation + 2L of Thermal Mass.
• Experiment started on morning of 19 October 2023 and is still running.
• NOTE - Red dot is actually - INTERNAL temp (temp probe taped to 2L Coke Water bottle)
• Blue dot - is EXTERNAL temperature (sorry - had to swap the probes around for this experiment).
• All this data is in the Tiny House 9 Folder. Link to Dropbox below.
• Tiny House 9 Folder - Thermal Mass Trial 23 Oct 2023

• Tiny House control (Tiny House 8) data
• This tiny House has R4 insulation - but no thermal mass.
• Display approx 4 hour temperature lag in comparison to outside temperature (approx 4 hours).
• Control house does not perform as good as Tiny House with thermal mass.
• Tiny House 8 Folder - R4 Insulation + No Thermal Mass 23 Oct 2023

Exploring Thermal Mass

Incorporating thermal mass into your miniature Passive House model is an excellent idea. Thermal mass plays a crucial role in stabilizing indoor temperatures and enhancing energy efficiency in real Passive Houses. Here's how you can add thermal mass to your model:

• Select Suitable Materials: Choose miniature materials to represent thermal mass in your model. Common options include small concrete blocks, ceramic tiles, or even simulated stone or concrete surfaces.
• Placement: Strategically place the thermal mass within the model. In a real Passive House, thermal mass is often located on the interior surfaces of the building, such as concrete floors or interior brick walls.
• Thermal Mass's Role: Explain the purpose of thermal mass in the model. It absorbs and stores heat during the day (from sunlight or internal heating sources) and gradually releases it during cooler periods, helping to maintain a stable indoor temperature.
• Heat Sources: Integrate a heat source into your model, such as a miniature light representing sunlight. Show how the thermal mass absorbs heat from the source during the day.
• Temperature Monitoring: Use temperature sensors to demonstrate how thermal mass affects the indoor temperature. Log temperature data to illustrate the thermal lag effect, where temperature changes occur more slowly in spaces with thermal mass.
• Simulate Day-Night Cycle: Create a day-night cycle within your model. During the day, illuminate the miniature heat source, and during the night, turn it off to simulate the release of stored heat from the thermal mass.
• Visual Demonstration: Use color-changing materials or heat-sensitive paints on the thermal mass surfaces to visualize temperature changes. These materials can show how the thermal mass absorbs heat during the day and releases it at night.
• Discussion: Encourage discussions about the benefits of thermal mass in maintaining comfortable indoor temperatures while reducing the need for active heating and cooling.

By adding thermal mass to your miniature Passive House model, you can help participants understand how this passive design strategy contributes to energy efficiency and indoor comfort. It also provides an opportunity to experiment with different thermal mass materials and placements to optimize the model's performance.

Calculating Heat Gain or Heat Loss

• It is easy to calculate how many Watts of energy entering or leaving the Tiny House using internal and external temperature measurements.
• The Energy flow is calculated using the following equation.
• The Area of the Tiny House (0.4m square) is 0.96m2 - which is very close to 1m2
• The ΔT (temperature difference) is the difference in internal and external temperatures
• The value of R is 4 m²K/W. This is very high level of insulation for domestic houses.

Energy flow (Watts) = Area x ΔT x 1/R

Energy flow (Watts) = (0.4 x 0.4 x 6) x (ΔT) x 1/4

Energy flow (Watts) = 0.96 m2 x ΔT degC x 1/ (4 m²K/W)=

On a 40degC Day, assuming an internal temperature of 20 degC, the Energy flow into the Tiny House would be:

= 0.96 x 20 x 1/4 = 4.8 Watts/hour

A simpler rounded calculation is simply

Energy flow (Watts) = (ΔT degC)/4

Energy flow (Watts) = (external Temp - internal Temp) / 4

Specific Heat Capacity - Water

• The specific heat capacity of water in SI units is approximately 4.184 joules per gram per degree Celsius (J/g°C) or equivalently 4,184 joules per kilogram per degree Celsius (J/kg°C).
• This means it takes 4.184 joules of energy to raise the temperature of 1 gram of water by 1 degree Celsius.

Energy Required to raise water temperature of 2L of water by 10°C

To calculate the energy required to raise the temperature of 2 liters (or 2,000 grams) of water from 15°C to 25°C (10°C), you can use the specific heat capacity of water (4.184 J/g°C). The formula to calculate energy (Q) is:

Q = m⋅c⋅ΔT

Where:

• Q is the energy in joules.
• m is the mass of the water in grams (2,000 grams in this case).
• c is the specific heat capacity of water (4.184 J/g°C).
• ΔT is the change in temperature in degrees Celsius (25°C - 15°C = 10°C).

Now, plug in the values and calculate:

Q = 2,000g⋅4.184J/g°C⋅10°C = 83,680J

So, it would take 83,680 Joules of energy to raise the temperature of 2 liters of water from 15°C to 25°C (10°C).

Conversion of Joules to Watt.hours

• 1 Watt = 1 J/s
• 1 Watt.hour (Wh) = 3600 Joules

Watt.hours = 83,680 (J) / 3600 (s) = 23 Watt.hours (Wh) (23 Watts for 1 hour)