Exploring commercial water end-uses for a retail building in Brazil

Technical Summary: Exploring Commercial Water End-Uses for a Retail Building in Brazil

Problem Statement
Effective urban water management and the development of conservation strategies in commercial buildings rely on a thorough understanding of water end-use patterns. While previous studies have established that commercial buildings are significant potable water consumers, accurate data regarding specific end-uses, flow rates, and operational habits remains scarce, particularly in the Brazilian context. Existing literature often relies on aggregated billing data or broad area-based indicators, which may fail to capture the heterogeneity of water demand across different commercial activities. Furthermore, the lack of detailed end-use data limits the reliability of demand forecasting models and the design of targeted water conservation programs. This study addresses the gap in detailed knowledge regarding water usage in retail buildings, specifically focusing on the need to characterize daily and hourly consumption patterns and develop performance indicators for demand management.

Methodology
The study employed a comprehensive water auditing approach within a two-story retail building located in the Lago Norte Administrative Region of Brasília, Brazil. The building houses seven distinct commercial establishments: a hardware store, bakery, grocery store, drugstore, beauty salon, bar, and pet shop, with a total built area of 2,116 m².

The methodology integrated three primary data sources:

1. Historical Billing Data: Monthly water bills from January 2013 to December 2017 were analyzed to assess long-term consumption trends and calculate average daily demand.
2. On-Site Technical Inspections: Researchers inventoried all water fixtures and appliances, mapped their locations, and collected operational data, including employee counts, customer flow, and specific activity metrics (e.g., bread production volume, number of hair washes, pet baths).
3. Water Audits with Flow Sensors: ½" turbine-type flow sensors were installed at each point of use and connected to data loggers. Monitoring periods ranged from 7 to 20 days per establishment, recording flow rates, duration, and frequency of use for every fixture.

Data analysis involved calculating standard indicators (litres per person per day [L/p/d] and litres per square meter per day [L/m²/d]) as well as activity-specific indicators (e.g., litres per kg of bread dough, litres per hair wash, litres per pet bath). To ensure accuracy, estimated consumption derived from sensor data was compared against billed consumption. A correction factor was applied to account for discrepancies caused by factors such as regional water crises, leakage, or meter-reading inconsistencies, resulting in "corrected" end-use demands and indicators.

Key Results
The retail building exhibited an average daily water consumption of 9,849 L/d (4.65 L/m²/d and 80.07 L/p/d). The study revealed significant variability in consumption patterns among the seven establishments, driven largely by their specific operational characteristics rather than their built area.

• Dominant End-Uses: At the building scale, kitchen sinks and toilet flushing were the primary water end-uses, accounting for approximately 44% and 21% of total demand, respectively.
• The Bakery Anomaly: The bakery, occupying only 13.9% of the total built area, accounted for approximately 61% of the building's billed daily water demand. Its consumption was driven primarily by snack bar operations and food preparation (kitchen sinks), rather than bread production itself.
• The Hardware Store Contrast: Conversely, the hardware store occupied 49% of the built area but contributed only 6.6% of the total water demand, with toilet flushing being its primary use.
• Activity-Specific Findings:
  • Beauty Salon: Water demand was heavily concentrated in salon activities (washbasins and hair washbasins), which represented over 95% of total consumption.
  • Pet Shop: Pet bathing activities accounted for 62.5% of the shop's demand, highlighting a service-driven consumption profile.
  • Bar: Toilet flushing (55%) and kitchen sinks (32%) were the dominant uses, with consumption heavily influenced by weekend events and extended operating hours.
  • Grocery Store: Consumption was entirely event-driven, linked to the washing of produce, with no continuous baseline demand.
• Temporal Patterns: Hourly analysis showed distinct peaks, such as a major demand spike at 15:00 driven by the bakery's operations. Weekly patterns varied significantly; for instance, the hardware store and pet shop closed on Sundays, causing a notable drop in overall building demand.

Key Contributions
The study expands the available database on water end-uses in commercial buildings by providing activity-specific water consumption indicators for a diverse range of retail and service activities in Brazil. It demonstrates that built area alone is an insufficient predictor of water demand in retail buildings. Instead, the research highlights the necessity of integrating operational characteristics—such as the type of service provided, production volumes, and customer flow—into water demand forecasting and management strategies. The development of specific indicators (e.g., L/kg/d for bakeries, L/wash/d for salons) offers a more granular basis for benchmarking and conservation planning than generic per-area metrics.

Significance and Claims
The authors claim that this study provides a necessary foundation for fine-tuning water conservation programs in retail buildings by moving beyond aggregate data to detailed end-use characterization. By revealing the substantial influence of specific operational activities (like bakery snack bars or pet bathing) on overall demand, the paper argues that water management strategies must be tailored to the specific nature of the commercial activity rather than the building's physical size. The findings underscore the value of detailed water audits in identifying leakage, understanding usage habits, and establishing realistic benchmarks for non-residential sectors. The paper concludes that further studies encompassing a broader range of commercial activities and urban contexts are required to develop more representative water consumption indicators and support sustainable urban water management.