Low-cost Sensors for Balancing Indoor Air Quality and Energy Usage

Abstract

Saving energy and improving indoor air quality (IAQ) and thermal
comfort in buildings are traditionally competing goals. Facilities that
manage one of these objectives tend to compromise the other. Building
automation systems (BAS) have been limited in their ability to sense
these characteristics of a building and therefore cannot act on them. A
majority of buildings define IAQ in terms of supply air temperature
alone, and manage energy consumption by scheduling. There is a
large potential to improve both IAQ and energy consumption through
innovative control strategies. These strategies are independent of de-
velopments in the energy conversion equipment itself by enhancing its
control. Good control requires good feedback, and feedback for IAQ is
complicated by a lack of sensors able to be easily integrated into BAS
that can record other contributions to IAQ such as CO 2 and the presence
of trace gases. Since BAS have not traditionally had access to these types
of data, there is little experience of how to best apply this new informa-
tion in a dynamic system to achieve reduced energy consumption while
improving IAQ. This article will discuss development and integration
of low-cost microsensor arrays into affordable BAS. Multi-function sen-
sor packages are in development that can measure CO2, temperature,
humidity, room occupancy, and potentially other trace gases of interest.
The sensor package can communicate with the BAS wirelessly or over
existing building power wiring. Communications have been developed
for a low-cost implementation with algorithms focused on security and
robustness.