Linked Web-Enabled Programmable Thermostats for Small and Medium Commercial Applications
Programmable Thermostats: Web-Enabled Programmable Thermostat for Small Commercial Application vs. Conventional
This technology allows remote access to HVAC equipment serving multiple zones for the purpose of remote control and optimizing energy efficiency.
Item ID: 247
Commercially available and new? True
Quantifiable and reliable electric energy savings? True
Will work as intended? True
Emerging Technology Type:
Energy Management, HVAC
Technical Advisory Group: 2010 E3T HVAC TAG
Average TAG Rating: 3.3
TAG Ranking Date: 06/29/2010
Technical Advisory Group: 2011 E3T Energy Management TAG
Despite the growing capabilities of programmable thermostats, field data generally shows that basic commercial building fan scheduling and occupied/unoccupied cooling and heating setpoints are very poorly executed, resulting in energy waste. Web-enabled smart thermostats can be monitored and controlled remotely so several zones or facilities can be controlled from a central location. This makes it easier for someone with expertise to monitor and make changes to several thermostats using similar energy-conserving strategies.
Companies such as Network Thermostat www.networkthermostat.com offers four communications platforms under which programmable thermostats can be linked and controlled for a multi-zoned commercial building. Communications protocols include Wi-Fi, Ethernet, mesh wireless (Zigbee) and direct wired systems. The selection of choice depends on WI-Fi access and router strength, IT firewall considerations, and the number and locations of thermostats to be controlled. System design occurs after a review of facilities diagrams, HVAC equipment sizes and types, and scheduling needs. A downloadable application---the device explorer---serves as a "command center" and allows a browser of choice to open up a tab for each programmable thermostat. This technology is suitable for businesses of any size.
BC Hydro recently tested 3 Ecobee thermostats in a small (7,500 square foot) cabinet shop. The thermostats controlled electric baseboard heaters, a gas-fired overhead radiant-tube heating system, and electric space heating in a trailer used as a lunchroom. The trailer heated was scheduled so that it only provided heating during the 3-break times during the day when it was occupied. BC Hydro found the smart thermostats easy to install and use. Energy savings targets were exceeded, with a savings of 45,000 kWh annually valued at $3,300. This amounts to 55% of initial use and provides a payback of 0.7 years. Cost of the three smart thermostats was about $1,233 with an additional $1,000 needed for work by electricians and additional WI-FI equipment.
Baseline Description: Status Quo
Baseline Energy Use: 120000 kWh per year per unit
Rooftop packaged HVAC units (RTUs) serve over 40% of commercial building space with relatively reliable air conditioner and furnace operation. RTUs are typically controlled by single-zone thermostats of a variety of types. Thermostats were originally simple electro-mechanical devices that provided a call for heating or cooling. Thermostats are made by a number of manufactures as an independent and interchangeable HVAC control component. The current trend is to incorporate digital electronics into these thermostats that provide sophisticated control features, networking capabilities, and interface features. Many existing RTU thermostats are at a minimum “programmable” for scheduling setpoints and occupied hours.
Manufacturer's Energy Savings Claims:
"Typical" Savings: 20%
Savings Range: From 10% to 30%
Best Estimate of Energy Savings:
"Typical" Savings: 20%
Low and High Energy Savings: 15% to 30%
Energy Savings Reliability: 3 - Limited Assessment
The energy savings due to incorporation of remotely controlled programmable thermostats are due largely to increased ability to more easily detect and correct improper schedules, setpoints, and operation of systems. This will require training and focused attention from the attendant energy managers.
Network Thermostat offers systems for any sized business by allowing multiple thermostats to be installed and linked to a command center by Wi-Fi, ethernet, or both. Their downloadable command center software can be loaded onto an PC. No hardware investment is required. One building owner (RS Clark) claims a 28% energy savings due to controlling seven 2 to 4 ton rooftop units with Network Thermostat equipment. The thermostats employed offer 6 different custom program settings for every day of the week. A limited over-ride feature allows temperature setpoints to be changed by up to 3 degrees F for a pre-set one to three hour maximum time interval.
BC Hydro recently completed a demonstration of the Ecobee smart thermostat. This product can be used in small business settings and wirelessly connect with a users PC or mobile device. The Ecobee smart thermostats cost $411 per unit and were used to control baseboard heating, an overhead radiant-tube heating systsm, and space heating in a shared lunchroom. The Ecobee thermostats resulted in a savings of 55%, valued at $3,300 per year for electricity and natural gas combined. The simple payback was only 0.7 year.
Energy Use of Emerging Technology:
96,000 kWh per unit per year
Energy Use of an Emerging Technology is based upon the following algorythm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
The EPA Energy Star buildings database shows an energy use of 31,000 Btu/ft-2 for medium sized, mixed use buildings for space heating. Cooling loads in Western WA and OR and very small. Heating is generally provided by natural gas---for this analysis, gas heat was converted to electrical energy use through multiplying by 0.8 (furnace efficiency) and then dividing by 2.5 which is an assumed heat pump efficiency. This yields a heating load of about 120,000 kWh/year (rounded up from 116,370). A 20% savings or reduction in space heating requirements would leave a residual or heating load given state of the art control of 96,000 kWh/year.
Currently no data available.
Installed first cost per: unit
Emerging Technology Unit Cost (Equipment Only): $3000.00
Emerging Technology Installation Cost (Labor, Disposal, Etc.): $500.00
Baseline Technology Unit Cost (Equipment Only): $0.00
The cost for web-enabled smart thermostats is not great and is declining rapidly. An Ecobee smart thermostat--capable of linking with other thermostats and wireless devices in a building---can be purchased for about $400 each. Network Thermostat models cost about $450 per thermost. A building owner (RS Clark & Associates) purchased a system with seven thermostats that controlled seven 2-4 ton rooftop units from Network Thermostat. The equipment cost, including a network controller, was only $3,016. Installation was done overnight (this system used Cat 5 cable running to a network controller) at a total installation cost of $560. Setup is facilitated as schedules can be copied from one thermostat to another. The building owner noted that the total changeover cost was less than his July electric bill.
InThrMa also offers both web and mobile interfaces for remotely managing HVAC systems. These thermostats allows load scheduling from remote locations and can display current and historical energy use data on a web portal accessible by PCs or mobile devices. There are often no annual license or software update fees. Proliphix also offers web and ethernet based thermostats for commercial buildings with a cloud-based software service providing HVAC management.
Simple payback, new construction (years): 1.4
Simple payback, retrofit (years): 1.6
Simple paybacks can vary greatly depending upon the features included in the system to be installed, the number of thermostats required, and whether wireless or ethernet cable communications are used. Savings and simple paybacks are also dependent upon how well the existing systsem is managed. A large house of worship (Colonial Baptist Church) comprised of 5 multipurpose buildings used a total of 19 thermostats to control HVAC units. They church building had a combination of standard and programmable thermostats with the disadvantage of widely varying schedules, last minute changes in events, and well-intended members of the congregation trying to "help" the facility engineer by modifying schedules and adjusting temperatures---and then forgetting to set the thermostats back when an event was concluded. Quoted prices for full Building Automation Systems (BAS) were in the $60,000 to $70,000 range. Wireless Network Thermostat products were ultimately purchased and installed with a simple payback of about 3 months. (The savings over a four month period were 166,700 kWh valued at $10,364).
This proposal is for a system of linked thermostats controlling multiple building zones to be accessed remotely via the Internet. This is a bridge between stand-alone programmable thermostats and a full Direct Digital Control (DDC) building automation system.
Standard practice is to use conventional programmable thermostats, which may have a locking cover so building occupants can not make setting changes that may adversely affect energy efficiency. Experience indicates that these units are not always programmed correctly which can result in heating unoccupied space.
A number of competing products offer most or all of the features and performance enhancements envisioned for this technology. A number of small focused manufactures have entered this market in the last few years. Product features are evolving and being adopted for use in controlling HVAC systems. Costs becoming lower for communications is helping to make this technology more viable.
End User Drawbacks:
This technology requires unit controls to be networked, and standard wiring in an existing facility may be problematic. Wireless controls are offered and seem an obvious solution. The equipment is more expensive, but the savings in installation by not having to run wires often more than compensates for the extra equipment cost, making this a more cost-effective solution than hard-wired. Each site requires an Internet connection with a wireless monthly subscription and related hardware including routers. Alternatively, local IT security policies may be negotiated to be able to incorporate it into existing systems while maintaining secure access.
Operations and Maintenance Costs:
No information available.
The life expectancy of the product is similar to that of DDC control equipment—approximately 15 years.
For larger facilities, an overhaul with a full-scale DDC system will likely provide more functionality and a better interface with a portfolio of buildings. This technology is likely to have a niche market for smaller buildings.
Reid Hart, PE
PECI Associate Director, Technical Research
503.961.6142 (ext. 324)
Reference and Citations:
Thermostat Interface and Usability: A Survey
Lawrence Berkeley National Laboratory
How people use thermostats in homes: A review
Building and Environment
How People Actually Use Thermostats
American Council for an Energy-Efficient Economy
2011 Residential Building Stock Assessment: Single-Family Characteristics and Energy Use
Northwest Energy Efficiency Alliance
Field evaluation of programmable thermostats: Does usability matter?
FPL Residential Thermostat Load Control Pilot Project Evaluation
Applied Energy Group, Inc.
Measure Summary Report: Web-Enabled Programmable Thermostats
Energy Experts Q&A
Washington State University Extension Energy Program
Technical Trials of Ecobee and Modlet at Gillingham Cabinets
Prior Research on this Emerging Technology:
Hart, R. (2008). “Premium Ventilation Package Testing: Decision Framework Matrix Report – Task 5.” Portland Energy Conservation, Inc. (PECI) for Bonneville Power Administration (BPA).
Hart, R. (2009). “Premium Ventilation Package Testing: Short-Term Monitoring Report – Task 7.” Portland Energy Conservation, Inc. (PECI) for Bonneville Power Administration (BPA).
Testing is currently underway to evaluate premium ventilation applications with thermostats capable of web interactivity.