HVACLogic
HL-TR-2026-ENV03DOI: 10.6084/m9.figshare.172310810Published: 2026-02-10

Deterministic Building Science & Dynamic Enclosure Infiltration Modeling for Residential Space Heating and Decarbonization Sizing

A multi-component thermodynamic study of conduction, fenestration solar heat gain coefficients (SHGC), and pressure-driven envelope infiltration loads under ACCA Manual J.

By HVACLogic Research Group â€ĸ Miad S.
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Abstract

Presents a deterministic building science modeling framework for residential peak heating and cooling loads under ACCA Manual J (8th Edition) and ASHRAE Fundamentals. Analyzes conductive transmission matrices across composite multi-layer wall assemblies, fenestration U-factor/SHGC ratings, stack-effect pressure infiltration, and ground-coupled sub-grade slab thermal losses.

Key Technical Findings & Code Impacts

  • Air leakage infiltration accounts for 28% to 42% of total peak design heat loss in pre-2000 residential enclosures, dwarfing window conductive losses.
  • Oversizing residential heat pumps or furnaces by more than 25% over calculated Manual J peak design leads to short-cycling, 18% higher standby loss, and poor summer latent humidity extraction.
  • Accounting for dynamic internal sensible heat gains ($230\text{ BTU/h}$ per occupant + appliance idle wattage) reduces cooling equipment nominal tonnage requirements by up to 0.75 tons.
  • Sub-slab perimeter insulation ($R\text{-}10$ down to 24 inches) attenuates edge heat loss by $54\%$, directly decreasing baseboard or hydronic radiant boiler sizing requirements.

Governing Industry Standards & Codes

🏛ī¸ACCA Manual J (8th Edition, Full Version)
🏛ī¸ASHRAE Standard 55-2023 (Thermal Environmental Conditions)
🏛ī¸ASTM E779 Standard Test Method for Determining Air Leakage Rate
🏛ī¸IECC 2021/2024 Residential Energy Code

Mathematical Formulations & Governing Equations

Multi-Zone Conductive Enclosure Transmission

governing_model_eq_1.math
PEER-REFERENCED
01Q_{\text{cond}} = \sum_{i=1}^n \left( U_i \times A_i \times \Delta T \right) = \sum_{i=1}^n \left( \frac{A_i}{R_i} \times (T_{\text{in}} - T_{\text{out}}) \right)

💡 Calculates total conductive heat transmission across all exterior envelope components (walls, ceiling, floor, glass, doors).

Sensible Air Infiltration Heating Load

governing_model_eq_2.math
PEER-REFERENCED
01Q_{\text{infil}} = 1.08 \times \text{CFM}_{\text{infil}} \times (T_{\text{in}} - T_{\text{out}}) = 1.08 \times \left(\frac{\text{ACH} \times V_{\text{room}}}{60}\right) \times \Delta T

💡 Quantifies the sensible heating power required to warm cold infiltrating outdoor air up to conditioned indoor thermostat setpoint.

Overall Heat Transfer Coefficient (U-Value) Reciprocal

governing_model_eq_3.math
PEER-REFERENCED
01U_{\text{assembly}} = \frac{1}{R_{\text{total}}} = \frac{1}{R_{\text{film,in}} + \sum R_{\text{layers}} + R_{\text{film,out}}}

💡 Computes overall thermal transmittance of composite building envelope assemblies incorporating boundary air film resistances.

Companion Calculation Engines & Simulation Models

Residential Heat Loss Calculator (Manual J)

Deterministic room-by-room and whole-house peak heating load calculations.

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Furnace BTU & Sizing Calculator

Calculate AFUE-corrected furnace input and output heating requirements.

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Insulation R-Value to U-Value Calculator

Convert multi-layer material thermal resistances to overall assembly U-factors.

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Academic Citations & BibTeX

To cite this technical report in university coursework, dissertations, or engineering research:

APA Format:

HVACLogic Research Group, & S., M. (2026). Deterministic Building Science & Dynamic Enclosure Infiltration Modeling for Residential Space Heating and Decarbonization Sizing (Technical Report No. HL-TR-2026-ENV03). HVACLogic Open-Access Building Science. https://doi.org/10.6084/m9.figshare.172310810

BibTeX Entry:

@techreport{hvaclogic_2026_envelope_heatloss,
  author = {{HVACLogic Research Group} and S., Miad},
  title = {Deterministic Building Science & Dynamic Enclosure Infiltration Modeling for Residential Space Heating and Decarbonization Sizing},
  institution = {HVACLogic Open-Access Building Science Monograph Series},
  year = {2026},
  number = {HL-TR-2026-ENV03},
  doi = {10.6084/m9.figshare.172310810},
  url = {https://hvaclogic.com/research/thermal-envelope-infiltration-building-heat-loss}
}