2/3/2015 MECH 8250 Ventilation Winter 2014 Lecture: February 2 nd 08/09/2014 1 Topics Covered by this Course • Building Ventilation Systems • BCBC 2012 • ASHRAE 62.1 03/02/2015 2 1
2/3/2015 Natural Ventilation 03/02/2015 3 Mechanical Ventilation 03/02/2015 4 2
2/3/2015 Mechanical Ventilation Dedicated Outdoor Air Systems (DOAS) 03/02/2015 5 Ventilation Standards BCBC 2012 3.3.5.7: Ventilation of Vestibules 6.2.2.3: For Storage Garage 9.32: Ventilation for Single Dwelling Unit ASHRAE Standard 62 – 62.1: Non ‐ Residential – 62.2: Residential (BCBC 2012 takes over) LEED (Leadership in Environment & Energy Design) ‐ 2004 03/02/2015 6 3
2/3/2015 VENTILATION – BCBC 2012 BCBC 3.3.5.7: Natural Ventilation: Unobstructed area of 0.1m 2 for each door that opens into the vestibule BUT not less than 0.4m 2 Mechanical Ventilation: 14m3/hr.m 2 (0.82 cfm/ft 2 ) for vestibule area 03/02/2015 7 BCBC 3.3.5.7 – Ventilation of Vestibules Natural Ventilation: Unobstructed area of 0.1m 2 for each door that opens into the vestibule BUT not less than 0.4m 2 Mechanical Ventilation: Supply 14m 3 /hr.m 2 (0.82 cfm/ft 2 ) for vestibule area 03/02/2015 8 4
2/3/2015 BCBC 6.2.2.3 – For Storage Garage Mechanical Ventilation: 1. Continuous supply of ventilation air @ 14m 3 /hr.m 2 (0.76 cfm/ft 2 ) of the floor area. 2. When CO and NO 2 is detected at higher levels, this ventilation air is increased. 6ACH. 03/02/2015 9 VENTILATION – BCBC 2012 BCBC 9.32.2: Ventilation during Non ‐ Heating Season 9.32.2.2: Natural Ventilation Table 9.32.3.3 Open areas for various rooms 9.32.2.1: Mechanical Ventilation 0.5 ACH for air ‐ conditioning spaces 1.0 ACH for NON air ‐ conditioning spaces 03/02/2015 10 5
2/3/2015 VENTILATION – BCBC 2012 BCBC 9.32.3: Ventilation during Heating Season 9.32.3.3: Principal Ventilation Exhaust Fan OR Dedicated Central Ventilation System 03/02/2015 11 VENTILATION – BCBC 2012 Changes implemented on December 19 2014: 1. The End of Exhaust ‐ Only Ventilation Systems. Exhaust ‐ only ventilation systems are being replaced by a system that includes both exhaust and supply. 2. Principal Ventilation System Requirements : Continuous Operation (24 hours a day) 3. The same Principal Exhaust Fan can be used for Washroom or Kitchen, but when the room is being used, the exhaust will increase to satisfy the exhaust requirements 03/02/2015 12 6
2/3/2015 VENTILATION – BCBC 2012 Ventilation during Heating Season 9.32.3.3: Dedicated Central ventilation System with minimum Ventilation rate 03/02/2015 13 Principal Ventilation System Exhaust Fan A SFD unit shall include: A principal ventilation system including supply (1) and continuous exhaust (2). The bathroom fan (2) provides continuous exhaust as the principal ventilation exhaust fan and intermittent, on command exhaust at a higher air flow rate as a bathroom fan. The kitchen exhaust is provided by a dedicated kitchen exhaust fan (3). The heated crawl space is provided with a dedicated fan (4) and at least one passive grille to the rest of the house (5). 03/02/2015 14 7
2/3/2015 Ducted forced ‐ air furnace The furnace ducting provides supply air to required areas of the dwelling unit and the bathroom fan is designated as the principal ventilation exhaust fan, operating continuously as the principal ventilation exhaust fan (see 9.32.3.5.) and intermittently as a bathroom fan (see 9.32.3.6.). 03/02/2015 15 Use of HRV in Ducted Furnace 9.32.3.4.(3) Using a ducted forced ‐ air furnace in the principal ventilation system. The HRV may act as the principal ventilation exhaust fan and may exhaust from more than one location in the dwelling unit. In this case, the bathroom and kitchen fans are not part of the principal ventilation system. 03/02/2015 16 8
2/3/2015 Topics Covered by this Course • General requirements • LEED Points • Ventilation requirements • Construction and O/M requirements • Energy Efficiency Options • Possible Coming Changes • Questions 03/02/2015 17 ASHRAE – LEED Points EQ Prerequisite 1: Minimum IAQ • EQ Prerequisite 2: Environmental Tobacco Smoke (ETS) Control • EQ Credit 1: Outdoor Air Delivery Monitoring for CO2 • EQ Credit 2: Increased Ventilation – at least 30% more than ASHRAE • 62.1 2004 EQ Credit 3.1: Construction IAQ Management during Construction • EQ Credit: Construction IAQ Plan before occupancy • 03/02/2015 18 9
2/3/2015 1. Purpose 1.1 The purpose of this standard specify minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. 1.2 This standard is intended for regulatory application to new buildings, additions to existing buildings, and those changes to existing buildings that are identified in the body of the standard. 1.3 This standard is intended to be used to guide the improvement of indoor air quality in existing buildings . 03/02/2015 19 2. Scope 2.1 All spaces intended for human occupancy excluding low ‐ rise residential (62.2) 2.2 Defines requirements for ventilation, air ‐ cleaning design, commissioning, installation and O&M 2.3 Additional requirements and other standards may apply (labs, healthcare, industrial, etc.) 2.4 May be applied to both new and existing buildings, not intended to be used retroactively 2.5 Does not prescribe specific ventilation rates for smoking spaces 2.6 Ventilation requirements based on chemical, physical, & biological contaminants 2.7 Consideration or control of thermal comfort is not included 2.8 In addition to ventilation, the standard contains requirements related to certain sources 03/02/2015 20 10
2/3/2015 2. Scope 2.9 Acceptable IAQ may not be achieved in all buildings meeting these requirements because of: – Diversity of sources and contaminants – Air temperature, humidity, noise, lighting, and psychological/social factors – Varied susceptibility in the occupants – Introduction of outdoor contaminants 03/02/2015 21 2. DEFINITIONS Acceptable indoor air quality: Air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction. Occupiable space: an enclosed space intended for human activities, excluding those spaces intended primarily for other purposes, such as storage rooms and equipment rooms, that are only occupied occasionally and for short periods of time. 03/02/2015 22 11
2/3/2015 Ventilation System 03/02/2015 23 6. PROCEDURES 6.1 General. – Ventilation Rate Procedure or IAQ Procedure for outdoor airflow values for mechanical ventilation systems 6.1.1 Ventilation Rate Procedure. – Prescribes rates & procedures based on typical space contaminant sources & source strengths 6.1.2 IAQ Procedure. – Requires calculation of rates based on analysis of contaminant sources, concentration targets and perceived air quality targets. 03/02/2015 24 12
2/3/2015 6. PROCEDURES Ventilation Rate Procedure Most commonly used method • Lookup table (simple) or Appendix A (complex) • Need zone air distribution effectiveness • LEED requires this method • Indoor Air Quality Procedure Design to maintain specific contaminant levels • Mass Balance Analysis • Methods used in similar buildings • Validation by contaminant monitoring • 03/02/2015 25 VENTILATION RATE PROCEDURE 03/02/2015 26 13
2/3/2015 VENTILATION RATE PROCEDURE 03/02/2015 27 Ventilation Air (OA) Calculation Step 1 V bz = R p P z + R a A z • V bz = Breathing Zone OA • R p = Outdoor Air Rate per person • P z = Zone Population • R a = Outdoor Air Rate per unit area • A z = Zone Floor Area (Net occupiable) 03/02/2015 28 14
2/3/2015 Ventilation Air (OA) Calculation Step 2 V oz =V bz /E z • V oz = Ventilation Outdoor Airflow in the zone • V bz = Breathing Zone Outdoor Airflow • E z = Effectiveness of the air distribution 03/02/2015 29 03/02/2015 30 15
2/3/2015 COOLING 03/02/2015 31 Induced Ventilation 03/02/2015 32 16
2/3/2015 HEATING 03/02/2015 33 Ventilation Air (OA) Calculation Step 2 V oz =V bz /E z • V oz = Ventilation Outdoor Airflow in the zone • V bz = Breathing Zone Outdoor Airflow • E z = Effectiveness of the air distribution 03/02/2015 34 17
2/3/2015 Multiple Spaces Vot = Vou/Ev • V ot ‐ Design OA intake flow • V ou ‐ Uncorrected OA intake • E v ‐ ventilation efficiency from Table 6 ‐ 3 or Appendix A 03/02/2015 35 General Requirements 4. OUTDOOR AIR QUALITY 5. SYSTEMS AND EQUIPMENT 03/02/2015 36 18
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