The following post in an excerpt from CSE live.
By David Sellers
Ask yourself if there is any problem with your home that has bothered you. For instance, is there a room that is uncomfortable relative to the others? Is the HVAC system noisy when it runs? Do you wish that your utility bills were lower and is that a realistic wish? As a side note, I suspect that everyone wishes that their utility bills were lower, But, for instance, my worst case heating bill is about $50 for gas. That’s probably because Kathy (my bride) and I have a small house, reasonably tight and well insulated in a mild climate with a high efficiency gas furnace; probably not much that I can do to meaningfully reduce the bill. That doesn’t mean there aren’t meaningful things I can do to improve the way I use gas, which is a non-renewable resource that generates atmospheric carbon when I burn it. But, given the modest cost (currently) to heat my home, the perspective driving the desire to improve things will need to be more holistic rather than economic - a lesson I think for our current bottom line driven society. Anyway, the point of these questions is to find out if there is something you want to target a test at. Probably 50% or more of the tests performed by commissioning providers in the field are targeted at solving a specific problem or verifying a specific level of performance. But, that doesn’t mean you can’t learn something if you don’t have a problem to target with your test. You can do an information gathering test and find out exactly how your house performs. Here are some ideas that come to mind.
Deploy a data logger outside that tracks relative humidity (RH) and temperature and then deploy several loggers inside tracking the same thing along with maybe some indication of occupancy like light level or the operation of an electric light, and maybe one that tracks furnace operation. Then plot concurrent data to see how the environment inside your house responds to changes in the ambient environment and the use patterns. For instance, what happens to the RH inside when you take a shower? At night, if your furnace has night set-back, how fast does the temperature in the house drop off relative to how fast the temperature outside drops off. How about RH? How does RH compare to specific humidity or dew point which is a more absolute indication of moisture level? (Some data loggers will calculate dewpoint an specific humidity basedo on the parameters they measure. But if not, you can figure it out from a psych chart). How does absolute humidity inside and outside compare and track?
Deploy a current or kW logger on your power panel and on some critical (large) loads like the your dishwasher or your washer and dryer or your water heater (if it’s electric) and plot concurrent data to see how much of an impact on total load each appliance has. Add more loggers to other circuits serving light loads and plug loads to see how you use energy in your house. Only do this if you feel comfortable putting CTs on your circuits or if you know someone who is an electrician or who is comfortable doling that for you if you aren’t. (Electricity, even at the voltages we use in our homes can be dangerous if you don’t know what you are doing or aren’t comfortable working around it. Never do anything with electrical wiring that you are not comfortable doing and/or have not been properly trained to do.)
Put a logger on your furnace to measure differential temperature and pick up fan operation. Or deploy or add another one to monitor filter pressure drop. Deploy another outside to track ambient conditions or download the data from the web using one of the techniques/sites discussed in the Functional Testing Guide. Use a rotating vane anemometer to traverse your return grilles and get an idea of air flow. Then, simply log the operating of the system and see what it tells you. For instance, how does the actual capacity of the furnace compare to the rated capacity? How does the cycling time vary with changes in outdoor temperature? If you have a night set back thermostat, how does that impact the operation of the system vs. the way it operates once the house is warmed up or, at night once the house has cooled off to the set-back temperature? How long does it take your filter to load up? (Generally, filters should be changed on pressure drop, not appearance or time ).
Use the rotating vane anemometer to traverse your return grills and get a feel for total system flow. Then traverse your supply grills and see how the flow is distributed. Is it fairly uniform on a cfm per square foot basis, or are their areas with a lot of air and areas with less? If the distribution is not uniform, is that because of the loads in the areas served? Or does your system need balanced? (Maybe there is a reason that one area is always hot or cold!)
If you have an electric water heater log its power consumption and then use that data to compare what would happen if you heated your water using one of the heat pump based technologies that’s out there or using a conventional gas water heater or using one of the high efficiencyinstantaneous type heaters. Look at both the source and site energy implications and the atmospheric carbon implications.
Some of you may be thinking “that’s all well and good, but what if I don’t have a data logger?” If you live in California in one of the public utility service districts, you are in luck. You can borrow a logger from the Pacific Energy Center’s tool lending library . This is (as us 60’s generation folks would say) a “free to the people” resource that is available to you as a utility customer. Many of the private utilities in California and other states offer a similar service. Another option is to simply buy a logger. For under $100, you can be off and running. For about $300, you can be logging just about anything.
Most companies don’t realize how their facility compares in terms of energy usage and efficiency because they don’t have key information about how their building is performing.
In order to determine a building’s energy efficiency, it is necessary to accurately assess its performance. Energy benchmarking provides an effective way to evaluate the energy consumption of a building to help identify potential energy cost savings opportunities.
Data loggers are important diagnostic tools that provide base-line energy measurements. Data loggers can be used to monitor a building’s energy performance which may include monitoring major energy-consuming equipment such as compressed air systems, boilers, hot water systems, chilled water systems, air handling units, indoor and outdoor temperature and electrical usage.
There are several factors to consider when benchmarking a facility, including:
- Identify benchmark goals: Determine the scale and objectives of the benchmarking project. Do you want to verify a facility’s base-line performance or perhaps identify operational and maintenance issues?
- Obtain documentation: Gather information about the facility. Utility bills offer history on the energy usage and cost associated with its existing performance. Other important documentation can include: floor plans, mechanical equipment schedules, and drawings of the buildings duct work and mechanical systems.
- Design a monitoring plan: Based on the information collected from step two, a monitoring plan can now be created. It is important to determine the monitoring metrics you want to include in the scope of the monitoring plan. Common monitoring variables include temperature, relative humidity, kWh, light on/off, and other HVAC system performance measurements which may include differential pressure gauge pressure and flow.
- Setup monitoring equipment: Note: A trained electrician should install the monitoring equipment in live electrical panels. It is important to select the optimum logging interval for your application. When monitoring transducers outputting pulses (such as kWh transducers for example) a logging interval no shorter than every 5-minute should be used.
- Collect and analyze data: After the data has been collected that was outlined in the monitoring plan, the data can be analyzed to create a details of the facility’s energy consumption. After analyzing the benchmarking results, it is important to identify cost saving opportunities and implement improvements.
Optimizing a building’s performance can improve energy usage and decrease utility costs while providing benefits to the environment. Benchmarking is an important way to accomplish these goals. It can provide information on how a building is currently performing and establish objectives for the future.
Resource Links:
: STEP 2.3: Benchmark http://www.energystar.gov/index.cfm?c=assess_performance.benchmark
: U.S. Green Building Council http://www.usgbc.org/Default.aspx
Live data from a HOBO U30 remote monitoring system collecting benchmark data can be seen here. 
In the world of sustainable building, green roofs are becoming more popular in new construction and renovation projects. The investment in covering a roof with soil and plants can pay off through mitigating storm water runoff, lessening the heat island effect, and offsetting interior heating and cooling costs.
Nicole Goldman, owner of ‘g’ Green Design Center, a Massachusetts-based company specializing in green building materials, recently installed an experimental green roof on her home located in Woods Hole, MA. Goldman’s green roof is covered with a layer of synthetic and natural drainage layers, soil, and a variety of low-maintenance plants.
To monitor conditions on her green roof, Goldman uses Onset’s HOBO U30/GSM Remote Monitoring System to track air temperature, humidity and soil moisture. When the water content in the soil drops below a specific level, the system sends an alarm notification to activate an irrigation system. Additionally, the data that the logger provides helps Goldman identify which plants thrive under what conditions.
Live data from Goldman’s green roof can be accessed here.
Relative humidity levels are often ignored in homes despite the fact that unsuitable levels can be unhealthy, increase heating and cooling costs, damage building components, and affect comfort levels.
Research has shown that high-relative humidity levels also support the growth of dust mites, molds and bugs that can lead to increased allergy symptoms and reduce indoor air quality (IAQ). However, little to no measured data is available on actual indoor humidity levels in homes across the United States.
Concerned about the impact that relative humidity has on a building’s performance, the U.S. Department of Housing and Urban Development paired up with Steven Winter Associates, Inc. (SWA), an architectural and engineering research and consulting firm, to gather temperature and humidity data in more than 50 homes across the country.
Three different regions are being targeted for the study – the warm, humid southeast, the cold northeast and the Pacific Northwest. To complete the study, household characteristic data will also be collected during the initial site-visit to the home, including occupancy levels, insulation levels, equipment efficiencies, envelope leakage and duct leakage.
To monitor temperature and humidity levels, SWA engineers selected HOBO® U12 data loggers from Onset.
The battery-powered devices will measure and record humidity levels around-the clock – even during power outages – and accompanying HOBOware® Pro software will convert the data into time-stamped graphs that can be displayed on a PC or Mac.
The data collected from this study will support efforts already underway by the ASHRAE Standard Committee 160P on “Design Criteria for Preventing Moisture Damage in Buildings” and others to develop moisture modeling tools and related technical standards. These models and standards will help improve a home’s performance by minimizing conditions associated with high moisture levels. Test homes for this study are currently being identified, and most initial site visits and data logger installations should be complete by the beginning of this summer.
