Historic buildings were typically designed before the development of modern energy standards. As a result, while they hold significant cultural and architectural value, they often exhibit lower energy performance compared to contemporary buildings.
The studied church represents such a case. As a historic structure with thick masonry brick walls and traditional construction, the building previously demonstrated relatively high energy consumption, particularly in its lighting system. The extensive reliance on fluorescent artificial lighting increased annual electricity demand and generated unwanted internal heat gains.
Given the building’s functional pattern—intermittent occupancy and specific operating hours—the efficiency of the lighting system plays a critical role in overall energy performance. Therefore, this project was initiated with the goal of reducing energy consumption while maintaining the spatial quality and architectural identity of the building.
1. General Objectives
2. Technical Objectives
These objectives served as evaluation criteria for all simulation scenarios conducted in the study.
The building retrofit was conducted through a sustainable architecture approach, focusing on envelope optimization and daylight utilization. The existing brick walls and their thermal mass were preserved, while the design strategy emphasized reducing energy demand and utilizing the building’s passive environmental potential.
An energy model of the building was developed in DesignBuilder, incorporating occupancy patterns and thermal properties of construction materials. The simulations focused particularly on lighting and heating performance to accurately evaluate the impact of each design modification.
The following parameters were analyzed to assess performance:
All interventions were selected to enhance energy performance while preserving the architectural and historical identity of the building:
These measures enabled the building to achieve substantial improvements in energy performance with minimal physical intervention.
In this research, DesignBuilder served as the primary tool for energy performance simulation. The proposed building model was standardized according to ASHRAE 90.1 to ensure a valid comparison between the pre-retrofit and post-retrofit conditions.
Analysis of the simulation outputs indicates the following:
Annual and monthly charts demonstrated that replacing fluorescent fixtures with LED lighting and installing linear dimming controls significantly reduced lighting energy consumption across all months. The use of daylight-guiding panels increased the penetration depth of natural daylight, reducing the need for artificial lighting during daytime hours.
Heating energy reductions were modest but meaningful. The thick masonry walls maintained their thermal mass behavior, moderating indoor temperature fluctuations, while the injected cellulose insulation reduced heat loss.
Envelope performance analysis showed that thermal resistance increased without disrupting the dynamic thermal mass behavior of the masonry walls. As a result, indoor temperature fluctuations decreased and more stable thermal conditions were achieved, reducing energy losses during colder periods.
This project demonstrates that targeted optimization of operational systems—particularly lighting—can significantly reduce energy consumption in historic buildings without extensive interventions or structural modifications.
Data-driven simulations enable precise identification of energy loss sources and accurate prediction of building thermal behavior, transforming design decisions from assumptions into measurable and scientific processes.
The Arizona historic church case study confirms that integrating energy analysis tools with architectural conservation principles provides an effective pathway to improving building performance and indoor comfort within the framework of sustainable architecture. Energy retrofitting not only reduces resource consumption but also enables existing buildings to comply with contemporary energy efficiency standards and sustainable development goals.
Such an approach provides a practical and transferable model for similar historic building retrofit projects.
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