Sustainable Insights          

When Governor Schwarzenegger signed the landmark Solar Water Heating and Efficiency Act of 2007, he launched the largest solar water heating program in our nation’s history. The new legislation calls for a 10-year program aimed at installing approximately 200,000 solar water heaters in homes and businesses throughout California. By creating this program, lawmakers hope to see a reduction of harmful emissions, increased energy efficiency and lower utility bills.

A recent study shows that families below the poverty line spend 19% of their income on utility bills. To alleviate this burden and ensure that energy conservation is widely accessible to California residents, the California Department of Community Services and Development and the Southern California Forum for Energy Efficiency, Environmental, and Human Services Providers (SCF) initiated a renewable energy pilot program. As part of the program, solar hot water heating systems have been installed in four of the 22 low-income, single family homes across the state.

Funded by the State Petroleum Violation Escrow Account (PVEA), this program, in particular, will monitor each of the study homes’ energy and gas consumption to determine the efficiency of the solar hot water heating systems.

Arleen Novotney, Executive Director of SCF, is leading the project.

“Our goal is to provide low-income homeowners with access to renewable energy solutions designed to decrease energy consumption and reduce energy bills,” explains Novotney. “For this program, we installed solar hot water systems in various climate zones across the state and will monitor the efficiency of the solar hot water heating systems.”

To monitor systems performance, Novotney chose web-based HOBO® U30 Remote Monitoring Systems manufactured by Massachusetts-based Onset Computer Corporation. The monitoring system consists of a GSM cellular-based data logging unit and sensors that monitor gas usage, cold and hot water supply temperature, solar collector water temperature, and hot water flow.

The HOBO U30 collects data at one minute intervals, 24/7 and the information is accessible via the web.

Novotney and her team can access the data from Onset’s HOBOlink™ website. “With HOBOlink, we can view the data anytime, anywhere we have access to the Internet.” says Novotney. “The ability to view data remotely allows us to see how the hot water heating units are performing without having to go back into the field to manually collect the data.”

According to Novotney, many factors are being considered for this study. The evaluation of these systems will include a snapshot of the costs associated with the homeowners’ gas and electrical usage, as well as the energy costs following the installations. The energy savings will be reflected by the climate zone, the household size, and fuel type.

“Since no one in our state has ever monitored the natural gas usage associated with a solar water heating unit, we wanted to track the consumption of gas when the solar power was on versus when the solar power was turned off,” explains Novotney.

So far, the collected data indicates that the solar hot water heating systems are helping. During daylight hours the system turns off and only turns back on at night. “This is the kind of data we needed to see,” explains Novotney. “We wanted to determine whether or not the systems were performing the way we hoped they would. The data showed us that during the day there is no need for the system’s gas or the electric power to turn on, and this will ultimately save homeowners money.”

According to Novotney, the HOBO U30 systems will continue monitoring the current test homes until October and then she and her team plan to change the location of the loggers to include additional test homes.

“We plan on using the HOBO U30 systems on each of the 22-test homes for the pilot study”, concludes Novotney. “We hope to have comparison data on all of the solar hot water hearing systems by next year.”

Onset recently assembled a roundtable to discuss the current role data loggers play in energy and retro-commissioning applications. Roundtable participants included: Adam Knickelbein, Summit Blue Consulting, Don Gray, US Innovative Green Technologies, and Stephen Pfeiffer, Energy Plus.

How do data loggers play into your overall performance monitoring strategy?

Don: Data loggers allow us to do full baseline testing on a facility before we do any upgrades, changes or modifications. We work with utilities to get Customer Directed Rebates (CDR) for energy-efficient projects that decrease electrical usage at our clients’ facilities – putting money back in their pockets. With the data loggers, we get extremely high quality data.

Adam: We do a lot of evaluation work for gas and electric utilities that implement energy efficiency programs. An important part of doing that is to measure the energy savings that they get from various projects. For example, when we are monitoring lighting runtimes, we often use light on/off loggers or current-activated switches. When we measure motor runtime we use 4-channel loggers with current transducers to monitor the energy usage and estimate energy savings

There is an increased need for precise and reliable data because we need to verify whether the energy savings is really there.

Stephen: Data loggers play a very big role in my job. I use the loggers mainly for retro-commissioning to measure how efficiently an existing HVAC system and other building systems work. I also use the devices to verify whether or not a system is working properly after a retrofit.

What particular challenges do you face with respect to data collection?

Adam: We have a lot of different monitoring projects going on simultaneously and have to go to a number of different sites to download the data. I know that there are a number of web-based loggers that allow you to get real-time data, but right now, we only use stand-alone loggers that don’t have web access.

Don: One of the main challenges we have faced in the past is sending a tech out to a site to collect the data. Historically we collect high-volume samples. Collecting data with a web-based system, like the HOBO U30, saves us time and money. It gives us the ability to access the data anytime without having to go out in the field.

Stephen: I find that at times it’s difficult to put the loggers on older systems. Another challenge I face is bringing a laptop into the field to activate the loggers.

How do you work with the data?

Adam: We usually export the data into a statistics software program. For example, if we are measuring lighting we will often look at a population of retail stores or office buildings to get a snapshot of the energy usage other buildings are using and then we are able to get an average based on the data.

Don: I export the data files into Excel. Our customers want to see a graphical interface of what’s happening with their data. When I prepare a report, I put the data into graphs to show everything that has happened during the entire lifespan of the project.

Stephen: I always export the data into Excel because it helps me get a clear picture about how a system is working and easily helps me identify problems.

Do your monitoring projects typically require trend logging, real-time data, or both?

Don: We need both. I need real-world data for a lot of our projects. However, in general, trending data is more important to us.

Adam: We are looking at trend logging mostly.

Stephen: I only need to look at trend data.

What are the most important product features you look for in a data logger?

Stephen: The most important feature for me is memory since I need to log a lot of data using short- time sampling rates. I also look for a logger that can withstand harsh environmental conditions. They have to be able to take a beating.

Don: For us, its ease- of-use. The more complicated the test equipment, the longer I have to train our techs to go out and collect the data. Data loggers have been historically created for scientific types, and I think that more work-a-day people are going to be looking for products that are easy to use for their monitoring projects.

Adam: Cost is a big one for us as well as ease-of-use.

The word geothermal literally means “earth heat.” We can capture the heat that is stored in the earth and use it to heat our buildings. The top 500 feet of the earth stores heat from solar radiation. Although the top 30 feet of the earth changes temperature with the seasons, below 30 feet, the ground stays fairly stable at the average yearly temperature of the air.

In Maine, for example, the ground remains at nearly-constant 50 degrees Fahrenheit. As the earth absorbs the heat from the sun, that heat is transmitted downward to a depth of approximately 500 feet.

The Chewonki Foundation, a Wiscasset, ME-based nonprofit educational institution and winner of the 2009 GreatNonprofits Green Choice Award, is leveraging the natural phenomenon to lower energy costs and reduce its carbon footprint. The Foundation recently installed a geothermal heating unit that will help heat its largest building on campus – the Center for Environmental Education. The geothermal unit will use heat collected from a deepwater well to warm the building’s radiant floors.

“The geothermal system we installed is expected to be energy efficient,” said Tom Twist, sustainability educator for Chewonki. “In fact, we’ve projected the system will function at one-third the cost of a traditional oil-heat system, and can be expected to pay for itself in 3-5 years.”

To help verify these claims, and determine if geothermal is a viable energy source option to fossil fuels, the Foundation installed a web-based energy logging system from Massachusetts-based Onset to measure the heating system’s performance.

The system, a HOBO U30-ETH, was funded through a grant from the Maine Public Utilities Commission (MPUC), which is interested in verifying that our geothermal system will be a more economical energy source over the traditional oil heat source we used previously. If the results look promising, the MPUC may consider incorporating geothermal systems into public housing projects.

The data logging unit, which measures, records and transmits system performance data to the web, is configured with a number of sensors. Two flow meters are connected to the well pump, which measure BTUs the system is producing and flow rates. A kilowatt sensor measures the electric draw of all the system pumps, including a number of tiny circulating pump and the larger heat pump itself. Temperature probes measure air temperatures inside and outside of the building, and well temperatures coming in and going out.

A real-time display of the data is transmitted via Ethernet to the web over HOBOlink®, an Onset-hosted server. Twist configured the webpage with a “public access” feature so faculty and students can log on to see the latest measurements, as well as measurements taken over past week and month.

“The web display of the data is a benefit to us for a number of reasons,” explains Twist. “First, I am not a programmer, and it’s unlikely that I could develop any kind of interesting way to view the data online. Having it published by Onset using their secure and dedicated server makes it easy for us to see what we need to see. Second, it makes the data widely accessible, which is great for our students who can log in and see firsthand how the system is performing.”

The Foundation will be collecting data on the geothermal heating system through the fall and winter seasons, and aims to have cumulative data to present to the MPUC in the spring of 2010.

“We should, however, know fairly quickly this fall if the system seems to be reducing energy costs and shrinking our carbon footprint,” said Twist.