ACHRNEWS

Diagnosing Others' Problems

November 29, 2010
Morse Zehnter Associates Consulting uses tools such as this HOBO portable data logger to provide environmental monitoring.

Morse Zehnter Associates Consulting (MZA) applies its expertise in building science along the Eastern United States, with offices in Troy, N.Y., and West Palm Beach, Fla. The HVAC consultant deals with problems in the built environment - you know, problems caused by somebody else.

MZA’s expertise is based on the staff’s experience in forensic architecture and materials science. The team of architects, engineers, and environmental experts provide an array of diagnostic services.

The company has become more involved in sustainable building design, acknowledging that every building has its own indoor environmental issues, largely caused by construction, operations, and maintenance practices. The company said it combines architectural, materials science, IEQ, and moisture dynamics knowledge to provide building sustainability insights.

Modern construction methods and materials, combined with increased insulation, for example, has resulted in a stock of buildings that could be more sensitive to moisture-related issues. MZA addresses these types of problems through material selection and building envelope design.

HARD DATA

Existing buildings, as well as new ones, are candidates for improved efficiency and sustainability. The company said it is familiar with guidelines and rating systems for optimum building performance, such as LEED and other systems. The company also applies life cycle costing to optimize the trade-offs between first costs and operating costs, to arrive at facility designs with the lowest cost of operation.

The company uses tools such as portable data loggers to provide environmental monitoring. In a South Florida school district, for instance, a number of problems were related to IAQ, as well as temperature and humidity control. There were disgruntled teachers “and many people pointing fingers,” said a company spokesman. The company used HOBO® data loggers to show that the problems occupants had been experiencing were not based on the age of the equipment - which was what they had suspected - but had more to do with its capacity, oversizing which had resulted in excess ventilation, which in turn led to excess humidity.

Ten temperature-humidity loggers were applied in about 200 schools over the course of a few years to provide pre- and post evaluations. The retrofit design was based in part on the data.

Carbon dioxide levels were charted for weeklong periods with the temp-rh loggers and Telaire CO2 monitors. After interpreting the data and applying ASHRAE 62.1, MZA determined correct ventilation rates, plus the time of day CO2 levels trailed off, allowing exterior fans to be turned off. The company used the data to show building officials that ventilation rates of 10 cfm outside air per occupant represented 13 percent of the operating costs, and could result in substantial energy cost savings.

The loggers were interfaced with the CO2 sensor using an RS-232 jack; the equipment was placed in thermostat boxes. The logger was oriented in a way that also allowed use of the light logging capability, which was useful in determining when rooms were unoccupied, or when corridor lights were left on. HOBOware® Pro software allowed the firm to take a quick look at the data. This was exported to Excel for more detailed analysis.

The results showed that the school was overventilating classrooms, which led to untreated humid areas.

Balancing IAQ with energy savings is not a new dilemma. Schools also tend to get a bad rap for being misengineered, but that is not always the case. Tools like data loggers can show real data to the people who are making the decisions - data that really gets their attention.

Publication date: 11/29/2010