Tec de Monterrey, 2021

IMPROVING HEAT FOR THE WINTER

This project took on a very human challenge: improving the quality of life in the Rarámuri community of Norogachi by addressing two critical issues: cold indoor temperatures during winter and dangerous CO₂ buildup from indoor stoves.

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The team began by characterizing the assigned house type: a log cabin with a triangular wooden roof, partially open at the top, with one small window and a dirt floor. These openings, while allowing smoke to escape, also caused major heat losses, making the interior uncomfortably cold during winter nights. The hypothesis was clear: closing these openings would improve thermal retention but risk CO₂ accumulation, requiring a mechanical extraction solution to ensure safe indoor air.

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A 3D CAD model of the house was created in SolidWorks and simplified for computational fluid dynamics (CFD) analysis in ANSYS. This allowed the team to perform simulations on:

• Drag forces – to determine if wind could structurally compromise the house.

• Heat transfer – to measure indoor temperature distribution under different configurations.

• CO₂ accumulation – to assess the risk of toxic gas buildup.

Key assumptions included average wind speeds of 10 m/s, ambient temperature of 5°C, and a stove temperature of 250°C. Solar radiation data was incorporated to simulate realistic daytime heating.

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Four drag simulations were performed: with open windows (front and lateral wind), and with closed windows (front and lateral wind).

• Open configuration: drag force ≈ 1,627 N; low uplift forces, no structural risk.

• Closed configuration: drag force increased to ≈ 1,956 N (≈20% higher) due to reduced airflow paths, but still well below the structural limits of wood (9.8 MPa).

Conclusion: closing windows and openings slightly increases wind loading but remains safe if the roof is properly anchored to prevent detachment during storms.

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Four thermal scenarios were modeled:

1. Open geometry, stove in corner: heat quickly escapes; floor-level temperatures remain low.

2. Closed geometry, stove in corner: heat retention improves dramatically, but air near the roof reaches >65°C, risking discomfort and material degradation.

3. Closed geometry, stove in center: heat distributes symmetrically, eliminating cold zones and improving comfort.

4. Closed geometry + stove with hood (campana): similar thermal distribution, with partial heat loss but controlled smoke evacuation, achieving the best balance between comfort and safety.

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CFD analysis of CO₂ dispersion confirmed the risk of indoor air contamination:

• Closed geometry without hood: CO₂ accumulates dangerously, increasing risk of asphyxiation, internal burns from hot particulates, and potential fire hazards from embers.

• Open geometry: CO₂ dissipates naturally but at the cost of significant heat loss.

• Closed geometry + hood: CO₂ levels drop to negligible values (~0.001 m³ of gas), providing a safe environment while maintaining heat.

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Based on the simulations, the team proposed a low-cost, passive solution:

• Seal windows and roof openings to minimize heat loss.

• Install a metal hood or simple pipe above the stove to guide smoke outside.

• Add natural thermal insulation (straw, cotton, or wood fiber) between walls, not on the interior surface, to prevent fire hazards.

• Optionally use absorbent materials near the roof to trap residual CO₂ and triangular side vents to promote minor air circulation.

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These recommendations were aligned with Mexican thermal insulation standards (NOM-018-ENER-2011) and safety guidelines for heating devices (NOM-012-SESH-2010), ensuring compliance with national regulations.

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This project combined CFD simulation, thermal analysis, and human-centered design to produce a practical, culturally sensitive solution. By closing openings and integrating a simple smoke extraction system, the proposal simultaneously improved thermal comfort and respiratory safety, a small intervention with a significant quality-of-life impact for the Rarámuri community

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Please find attached below the relevant documents to this project. (Note: most, if not all documents, are in Spanish)