AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Ultrafine Particle Dynamics in a Net-Zero Energy House: Application of a Building Energy Management System for Evaluating Source and Loss Processes
JINGLIN JIANG, Brandon E. Boor, Purdue University
Abstract Number: 813 Working Group: Indoor Aerosols
Abstract Research on net-zero energy buildings (NZEBs) has been largely centered around improving building energy performance, while little attention has been given to indoor air quality and aerosols. An important step towards improving indoor air quality in NZEBs is understanding how occupants, their activities, and building systems affect the emissions and fate of ultrafine particles (UFPs). New developments in building energy management systems (BEMS) and smart thermostats offer a unique opportunity to track occupant activity patterns and the operational status of residential HVAC systems. The objective of this study is to investigate how a BEMS can be used to characterize time-variant UFP source and loss processes in an occupied residential NZEB.
A one-month field campaign was conducted at the Purdue ReNEWW (Retrofitted Net-zero Energy, Water, and Waste) House. Three adult residents occupied the house throughout the campaign. A scanning mobility particle sizer and optical particle sizer were used to measure indoor aerosol concentrations and size distributions from 10 to 10,000 nm. AC current sensors monitored electricity consumption of electrical kitchen appliances (cooktop, oven, toaster, microwave), the air handling unit (AHU), and the energy recovery ventilator (ERV). Two smart thermostats informed the fraction of supply air delivered to the basement and main floor of the house. BEMS-based data was integrated with the aerosol measurements and a material balance model to determine size-integrated UFP (10 to 100 nm) source and loss rates.
The ReNEWW House BEMS data identified hourly and weekly use-profiles and active emission periods of the four electrical kitchen appliances and the runtime of the HVAC system. The BEMS identified cooking activities as the dominant UFP source in the ReNEWW House, often elevating indoor UFP concentrations beyond 10,000 cm-3. UFP concentrations were the greatest when using the oven, with a median value of 6,400 cm-3. Kitchen appliance usage was most frequent between 10:00 and 14:00 and 18:00 and 21:00. Mean number size distributions for each appliance were determined during active emission periods and exhibited modal diameters between 20 and 50 nm. The HVAC system runtime exhibited a diel trend, thereby driving transient variations in HVAC-associated UFP source and loss processes. The AHU runtime peaked at around 10:00, reaching 74%, and was the lowest from 02:00 to 07:00, at around 36%. The ERV operated on a fixed schedule with a runtime of 36%. UFP source rates for the kitchen appliances inferred from the BEMS-aerosol data varied from 1011 h-1 to 1014 h-1. Median UFP loss rates when the AHU/ERV were off and on were 1.4 h-1 and 3.7 h-1, respectively.