iaq applications Energy-Efficiency Strategy Reduced Outdoor Air Ventilation Rates Increased Thermal Insulation Cooling Equipment Efficiency Increases Comment Increases concentrations of contaminants with indoor sources Can increase the likelihood of condensation in building envelopes (leading to potential biological growth) if increases are not well designed; can reduce likelihood if well designed May increase indoor humidity levels (leading to potential biological growth) if system design, control and operation do not adequately address latent loads table 1: Energy-efficiency strategies that may negatively impact IAQ. Energy-Efficiency Strategy Improved Moisture Management To Reduce Potential for Bioaerosol Growth Contaminant Source Control Improved Cleaning And Maintenance Practice Integrated Pest Management Comment If wetting of thermal insulation is reduced in the process, that will improve thermal performance Assuming no concurrent reduction in ventilation rates Reduces exposure to dust and to chemicals associated with cleaning products Reduces exposure to allergens and irritants associated with pests and to pesticides. table 2: IAQ improvements that are energy neutral. Strategy Heat Recovery Ventilation Comment Maintains outdoor air ventilation rates Mandatory in some energy efficiency standards Enables reduced ventilation at low occupancy Mandatory under Standards 90.1 and 189.1 Allowed by Standard 62.1 Must maintain baseline ventilation for non-occupant sources Sensor performance can be an issue Less mechanical cooling, more outdoor air Inappropriate when outdoor air is polluted and not filtered/cleaned, and when outdoor air is very humid Must maintain sensors and controls Potential to reduce energy use and improve ventilation Potential to simplify controls Easier to clean, condition and control outdoor air More flexibility in heating and cooling strategies Less outdoor air with same or better IAQ Not applicable in all spaces Less outdoor air with same or better IAQ Occupants prefer individual control Less mechanical cooling, more outdoor air Outdoor air pollution and humidity can cause complications Limited design tools and methods for performance measurement Infiltration is bad for energy and IAQ Must consider moisture dynamics within building envelope Contributes to both energy efficiency and good IAQ More significant in residential and small commercial buildings particularly when ductwork is in unconditioned spaces Improved equipment efficiency, cleaner supply air Filter installation and maintenance critical Less outdoor air with same or better IAQ No methods of test or rating standards for gaseous air cleaning Standard 62.1 Ventilation Rate Procedure does not allow ventilation reduction Less outdoor air with same or better IAQ Source characterization methods not mature Information lacking on key contaminants and design values Standard 62.1 Ventilation Rate Procedure does not allow ventilation reduction Contributes to both energy efficiency and good IAQ System access is key Demand Controlled Ventilation Economizer Operation Dedicated Outdoor Air Systems Displacement Ventilation Task Ventilation/Occupant Control Natural/Hybrid Ventilation Envelope Tightness Air Distribution System Tightness Enhanced Particle Filtration Gaseous Air Cleaning; Lower Ventilation Rates Source Control and Lower Ventilation O&M/Recommissioning table 3: Strategies that can support both energy efficiency and IAQ. 78 ASHRAE Journal ashrae.org October 2010