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Field Test Best Practices: A Resource for Practical Residential Building Science

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Occupied Houses

Occupants introduce realistic loads to a house system. Occupants introduce sensible and latent load through their body heat. In-house activities, such as turning lights on and off and using home appliances and miscellaneous electrical equipment, also introduce sensible and latent load. Opening and closing of windows brings in natural ventilation.  

Occupant behaviors, because they're varied and difficult to predict, also create the biggest uncertainty and challenge in testing, monitoring, and analyzing building system performance.  You may want to simulate occupancy in a test house to test the performance under controlled conditions.  This is also useful when you need to test a new system that may not provide adequate comfort conditions.

Thermostat Operation

It is common today to have programmable thermostats in new homes and in many existing homes as well. The sensor technology generally consists of thermistors with a heat or cool anticipation function. These thermostats generally have three or four wires connected to their terminals for sending and receiving heating, cooling, and fan signals to and from indoor air handling unit. In older homes, bimetallic switching thermostats are still used.

Occupancy Sensor

Occupancy sensors are widely applied for lighting control in commercial buildings for spaces with frequent on/off uses such as conference rooms, classrooms, and restrooms. There are two types of occupancy sensors: ultrasonic and infrared. Ultrasonic sensors detect sound, while infrared sensors detect heat and motion. Each technology alone is not totally reliable, which can cause inconvenience when using the sensors to control lights. Combining sound, heat, and motion detection can potentially generate decent savings without causing complaints.

Thermal Comfort

Short term thermal comfort evaluations are sometimes conducted in Building America field test houses to evaluate the thermal comfort effect on different types of windows, sliding glass doors, window shades and radiant heating and cooling systems.

Domestic Hot Water (DHW)

There are many different types of water heaters for houses. In addition to the efficiencies of individual water heating technologies, usage characteristics and hot water distribution play a large role in determining the total energy use due to hot water. Because DHW-related energy use is so occupant driven, for monitoring unoccupied houses it may become necessary to implement scheduled draw profiles.

Privacy and Security

Homeowner privacy needs to be a priority during a Building America field test, because many occupied monitoring tests will reveal occupant behaviors. See human subjects testing for much more on privacy policy. Additionally, implementing non-intrusive or minimally intrusive monitoring techniques should be followed as much as possible. For instance, installing a data logger in the garage is a better choice than in the living space, because not only is the data logger easily accessible to the researcher, but also it has minimal disturbance to the homeowner.

Security precautions need to be carefully taken at the project planning stage to ensure successful long term monitoring. There have been cases of field test sites having equipment and instruments stolen and vandalized in the past, which caused significant loss of time and money.

Simulated Occupancy

For long term monitoring in an unoccupied house setting, occupancy simulation is often needed to fully stress the house HVAC system. The uncertainty of occupant behavior and inconvenience prevent the long term monitoring from becoming common field test practices in occupied homes. Building America House Simulation Protocol (HSP) prescribes a "standard" set of hourly occupancy profiles that impose realistic, but known loads to the building systems [1]. In general, occupancy load generation can be categorized into internal heat gain generation, both sensible and latent heat loads, and domestic hot water generation.