The Environment Protection Agency in the United States is aimed at regulating industry to protect human and environmental health. Their research shows that Americans, on average, spend approximately 90 percent of their time indoors, where the concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations.

There is much research on how indoor and outdoor conditions effect health and the world is growing more aware of the potential dangers of the air they breathe. In fact, the EPA published a uniform index to help the public categorize air quality levels and mitigate the risks associated with each.

Indoor air quality can be affected by many factors including the air exchange rate, outdoor climate, weather conditions, and occupant behavior. Indoor concentrations of some pollutants have increased in recent decades due to such factors as energy-efficient building construction (when it lacks sufficient mechanical ventilation to ensure adequate air exchange) and increased use of synthetic building materials, furnishings, personal care products, pesticides, and household cleaners.

Use of handheld sensors give a point in time reference into the building air quality. Actively monitoring and controlling the impacts of these sources is the first step in building a healthy and productive workspace. Use of installed air quality sensors reporting in real time via cloud based sensor dashboard aides facility managers and stakeholders with actionable data to see trends and proactively building systems and activities to improve air quality.

This case study discusses an energy recovery ventilation system designed for an Army North facility major renovation project in south Texas. The building was originally cooled by multiple two-pipe indoor air-handler units fed by an air-cooled chiller and gas-fired boiler. Outside air was provided to the air-handlers from window louvers and roof vents. Such a ventilation approach is not recommended by the Unified Facilities Criteria (UFC’s), ASHREA 90.1, or industry standards.

The proposed replacement consisted of a Dedicated Outside Air System (DOAS) coupled with fan coil units to handle the envelope and ventilation loads separately. UFC 3-410-01 Section 4-2.4.1 requires ventilation for occupied spaces to be calculated based on the ventilation rate procedure specified in ASHRAE Standard 62.1. Occupancy detection based on indoor carbon dioxide concentration for ventilation is prohibited. This led to a potential for high volume of outside air intake and thus a heavy cooling load to properly ventilate the building.

The design team then examined the approach of preconditioning with energy recovery wheels. Outside air was pre-cooled by the energy recovery wheel with the heat transferred from exhausting air. The system was capable of pre-cooling the total ventilation air from 99.3 0F to 86.7 0F, which contributed to a reduction by 8.54 tons of the primary cooling coil. The chilled water valves were designed to modulate the DOAS units to maintain 55 0F leaving coil temperature in cooling. While this approach deviated from UFC 3-410-01 Section 3-2, which requires neutral temperature air supply for DOAS units, it complies with ASHRAE 90.1 section 6.5.2.6 “Ventilation Air Heating Control.” This was a well-documented modern approach and in accordance with the most up-to-date industry practices.

Can we justify increased ventilation?

Is it affordable, can we apply Energy Recovery Technologies & what to use?

Why is EATR & OACF critical to a designer