Following the Nest Path to Energy Efficiency
- March 5, 2015
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Following the trail blazed by Nest, firms like Ecovent are demonstrating that considerable efficiency improvements can be achieved through technology. The Nest thermostat is notable for matching the use of heating and air conditioning equipment to actual times of building occupancy and intuitively adjusting the temperature to a desirable level. Noticeably absent is the ability to optimize the inner workings of the equipment that is connected to the thermostat. Specifically, smart thermostats are adept at calculating when to best start/stop equipment; however, they are limited in their capacity to keep furnaces firing at peak efficiency or for assisting air conditioning fans from working harder than necessary. The next step in technology-enabled efficiency is to expand the optimal operation of HVAC equipment by enabling thermostats to feed information back to furnace computers, such as when a room is approaching the desired temperature or changes are on the horizon. This information would allow the HVAC equipment to run at peak efficiency for the largest possible percentage of each day.
High efficiency HVAC systems have the potential to squeeze nearly all of the energy out of natural gas and electricity. However, this is just potential. On paper, the best new heating equipment can achieve efficiencies as high as 98%. The systems-maximize performance via onboard computers that make micro adjustments to factors such as fan speed, furnace flame intensity, or the run time for air conditioning. However, optimal ratings are generally only achieved under ideal conditions whereas “real world” energy savings can be substantially lower than those published. For example, when air ducts or radiators in a particular home or building are not properly sized, systems try to compensate by running fans harder or burning gas outside of peak efficiency settings. Furthermore, because manufacturers know that many installations are far from ideal, they equip on-board computers with a myriad of switches and dials that allow installers to “tune” the equipment. Unfortunately, these overrides often carry sizable efficiency penalties. As shown in the figure below, making the wrong adjustments can result in equipment that operates only marginally better than what was available in the 1970s. Two-way communications between new smart thermostats and equipment promises to automate the optimization of performance. Furthermore, start-ups like Ecovent are demonstrating that heating ventilation and air conditioning (HVAC) installations can be made notably smarter by expanding wireless control to the room level.
The addition of new monitoring sensors can ensure that equipment automatically meets its efficiency capabilities. Wireless communicating temperature and pressure sensors installed in system air ducts or other strategic locations can communicate when increases in fan energy or raising the temperature are not resulting in measurable improvements in occupant comfort. In short, enabling communication and adding technology would greatly maximize the number of run hours that HVAC systems spend at peak efficiency and continue the progression that has begun with new smart thermostats.
Enhanced HVAC systems can also be used to assist in identifying the problem areas of buildings and targeted opportunities for improvement. The majority of HVAC systems are not able to operate within the most efficient range because a small area of a home is drafty or air ducts that are not designed properly serve one section of a building. Communicating technology can pinpoint problem areas, making the upgrade a decided advantage. Furthermore, identifing the problems responsible for poor performance allows for active calculation of how much defects are costing. In summary, expanded communication and data promises to assist utilities and energy service providers in identifying and quantifying favorable upgrade projects in energy efficiency.