CHIATECH JOURNAL · Registered Version of Record

Coupled Mathematical Modelling of Building Envelope and Cooling-Efficiency Standards for Nigerian Multi-Unit Housing: An Abuja-Calibrated BEEC–SONMELS Predictive Scenario Framework

1. Abdulsalam A. Abdulrahman
2. Shiaondo Kenneth Chia

Abstract

Background: Nigeria now has two complementary efficiency instruments that operate at different scales: the 2017 National Building Energy Efficiency Code (BEEC), which constrains building design and regulated loads, and the 2026 Standards Organisation of Nigeria Mandatory Energy Labeling Scheme (SONMELS), which classifies air-conditioner efficiency by the Nigeria Seasonal Energy Efficiency Ratio (NSEER). Their combined energy implication for multi-unit housing has not been expressed in a transparent mathematical crosswalk. Objective: This study couples the published Abuja-calibrated BEEC multi-unit apartment benchmark with current SONMELS cooling classes to quantify whole-building energy consequences under explicit cooling-service stress. Methods: The model uses the BEEC technical-study archetype of 1,200 m² with annual intensity components of 22 kWh/m² for lighting, 116 kWh/m² for cooling and 25 kWh/m² for water heating. The BEEC study reports 49% annual savings and 52% peak-load savings over regulated loads for the multi-unit benchmark. The 49% regulated-load result is reconstructed using the BEEC lighting-power-density change from 13 to 6 W/m², leaving a consistent residual cooling component. That component is then crosswalked to the SONMELS 1–5-star lower-bound NSEER thresholds (3.10, 3.60, 4.20, 4.95 and 5.80) under a cooling-service multiplier κ = 0.8–1.3. Results: The published business-as-usual archetype corresponds to 163 kWh/m²·year or 195.60 MWh/year. Reconstructing the BEEC benchmark gives 95.38 kWh/m²·year or 114.46 MWh/year, a 41.5% whole-site reduction when the unchanged 25 kWh/m² water-heating component is retained. After the BEEC package, movement from the 1-star analytical reference to the 5-star threshold reduces modeled site energy from 114.46 to 80.81 MWh/year, a further 29.4% reduction and 58.7% below the original archetype. Even under a 20% cooling-service stress (κ = 1.2), the BEEC + 5-star scenario remains at 88.54 MWh/year, 54.7% below the baseline. Conclusion: Building-envelope compliance and appliance efficiency are multiplicative rather than substitutable. The most resilient pathway for Nigerian multi-unit housing is to reduce cooling service demand through BEEC-compliant envelope and lighting measures before improving equipment efficiency through SONMELS. The results are a standards-coupled reanalysis of published and official evidence, not new field measurements.

Keywords: building energy efficiency; BEEC; SONMELS; multi-unit housing; cooling; air conditioners; NSEER; mathematical modelling; Abuja; Nigeria

Licence: Creative Commons Attribution 4.0 International (CC BY 4.0)

Published by CHIA TECH SOLUTIONS AND RESOURCES LIMITED. ISSN assignment remains pending.