Overview Finish up reactor models Project

Overview • Finish up reactor models • Project equipment • Ventilation standards • Turner et al. (1995) Occup. Med.

House of Pressure Demonstration • • POSTPONED UNTIL THURSDAY Blower door pressurization Combustion safety Pressure diagnostics (series leakage)

Equipment for Project • Temperature/RH – Hobo, Onset Computing • Additional air/water/soil sensors • Current, voltage, light sensors • CO 2 – Telaire 7001 connected to Hobo • Blower door and Duct Blaster – Energy Conservatory • DG 700 Digital pressure gauge and ATP • Particles, Side. Pak and P-Trak, TSI inc. • VOCS – Rae Technologies PPBplus (on order)

Things to Think About • What is the accuracy of the instrument in the range that you are going to be using it? • Is your signal going to be bigger than noise? • What is the output and how are you going to to use it? • Learning how to use devices • Scheduling

Relaxing Assumptions 1. Well-mixed • Use a CFD model 2. Constant air density • Track mass flows rather than volumetric flows 3. Constant variables (emission, etc. ) • Use a numerical solution 4. First–order loss and reaction processes • Use a numerical solution

Ventilation Regulations • ASHRAE Standard 62 -2001 • Minimum guidelines • Only consider pollutants • Not thermal comfort, Not energy use

Standard 62 • Table 2 lists outdoor air requirements • Correctional Facilities • Cells 20 CFM/person • Schools • Classrooms 15 CFM/person • Separate guidelines for residential buildings

Standard 62 • Nice summary of regulations (referenced) about indoor pollutant regulations and guidelines • Appendices C-G detail modeling techniques and parameter calculations

Questions • Do classrooms in ECJ have adequate ventilation? • How could we measure the ventilation rate? • Some amount of air is recirculated. • Is the classroom well-mixed? • Is the steady-state assumption reasonable? • What parameters would we need to measure?

Data From Two Years Ago

CO 2 in ECJ 9. 236

Three years ago (~same time) • 50 CFM/ person • Css = 486 ppm • Has ventilation been reduced to save energy? • How does ECJ control ventilation flows?

ASHRAE Standard 62. 2 • Low-rise residential buildings • Approved late 2003 • Huge politics • • • CO monitors Filter efficiency ETS Required mechanical ventilation Unvented Fireplaces

CO monitors • Gas industry scuttled requirement for CO monitors • False alarms • Limited life • “Go gas, go boom” • Electric utility slogan from 1950 s

Filter Efficiency • Elevated levels of particulate matter causes increased sickness and death • Typical furnace filters are ineffective and protecting humans • Standard requires MERV 6 • Very little opposition • Requires better HVAC design

ETS • ETS is a significant health concern • Tobacco industry has two main arguments • Pollutants can be controlled with ventilation • Not ASHRAE/government’s job to legislate behavior • ETS is mentioned as positively as possible in the standard

Mechanical Ventilation • Over the past 100 years houses have become significantly tighter • Moisture and other IAQ problems • Two main options for ventilation: • Mechanical ventilation like a commercial building • Always get air from outside • Exhaust only ventilation

Ref: Rudd www. buildingscience. com

Exhaust Ventilation

Comparison of ventilation options? • • First cost Operating cost IAQ Unintended airflows • Net result – NAHB voted against Standard 62. 2 • Balanced mechanical ventilation not required

Unvented Fireplaces • Very poor idea • Legal in 47 states • http: //www. fmconline. net/comfortglow/firepla ces/full_size. html • By law, unvented units must have oxygen depletion sensor • Unclear whether sensor protects occupants

Unvented Fireplaces • Standard suggests avoiding or minimizing their use • If there were no special interests: • Ban on unvented fireplaces • Examine literature on unvented cookstoves • Kirk Smith and others

Standards • It is better to have than to not have • Constant tension between usable standard and technically correct standard • Comes from a consensus process • One person/interest can scuttle standard • Often standard is tenuous solution that tries to please everyone • Once a standard is written, it can be easily “gamed”

Turner et al. (1995) • Excellent historical summary • e. g. smoking • Good description of different ventilation systems • Backdrafting, moisture problems • Use of CO 2 as ventilation metric • Disadvantages?

Human Exposure • Indoor air is largely about health effects • What mass of environmental fluids (air, water) do we ingest over a course of a day?

What metrics for human exposure? • Concentration • http: //www. epa. gov/air/criteria. html • Exposure • Dose • Absorbed dose

Does Concentration Matter? • Concentration • Varies in space and time • Exposure • Dimensions of concentration × time

Presented Dose • How much gets into body • Dimensions of mass (usually)

Absorbed Dose • Not all of a dose is absorbed

Summary • Concentration is not enough • Ventilation has significant impact on indoor air quality • You have tools for models • Next class • Energy impacts of ventilation