Spring 2012 Forum
Is Your HVAC Out of Control?
Making Sense of DDC Retrofits and Upgrades
March 16, 2012
NW Natural Building, Portland
Our Spring Forum, held on March 16th at the Northwest Natural headquarters in downtown Portland, was a resounding success. This forum focused on HVAC Controls and featured high quality presentations, controls vendors eager to answer questions, and a record turnout of attendees. The forum included an introduction to controls, a primer on controls protocols, advanced controls strategies for outside air and VAV, a talk on the importance of graphics and commissioning, a candid discussion about contractor short-cuts and implementation, and a case study of the controls upgrades at the Portland Art Museum. We finished up the day with a legislative update on the end of BETC and the new ODOE energy incentive program for businesses.
Bruce Dobbs of Mechanical Systems Engineering started the day off with an introduction to controls. Bruce began with a history of controls, reminding us of the times when “controls” meant manually turning hand valves and manually firing up boilers. Proportional Integral Derivative (PID) controls first showed up as a controls system for navigating ships in 1911. Pneumatic controls appeared in 1920s and were first used for boiler controls. DDC systems were adopted by the marketplace beginning in the early 1980’s. The controls of the time were rudimentary at first, but within 5 years, PID controls were incorporated into the new DDC systems. By the late 1980s another important milestone changed the world of digital controls – distributed controls could be managed by a frontend interface which increased reliability and control. Bruce introduced many foundational ideas like the sequence of operations, the points list, PID controls and commissioning. See His Presentation
Eric Shimmin of ECS Automation gave his presentation on the often bewildering topic of controls protocols. Eric’s presentation was designed to help us gain a little working knowledge about some of the controls concepts that are stubbornly difficult to understand. Eric taught us the function and meaning of the concepts of controls Media, Transport and Data Protocol by introducing the metaphor of a railroad.
In this metaphor, Media is the railroad tracks. Information moves on the media like a train moves on railroad tracks. Transport is like the train. The train determines the destination or address and the speed. The freight cars of the train accept up to a certain size of goods; this is like the different packet sizes that are accommodated by different types of transport. The Data Protocol is the actual data, which corresponds to the freight that the train carries. The protocol determines the language of the data.
Eric taught us how different protocols that work on certain media, and certain protocols need transport and data configured in a specific way. To interface between these different components, equipment must be compatible between the media, transport and data protocol.
Compatibility is another complicated issue to which Eric introduced us. There can be compatibility issues between different types of media, transport and data protocols, as well as within the same types of components that are from different years. Eric recommended that we consult the BacNet Testing Laboratories, BLT List to check on the compatibility of potential components. See His Presentation
Reid Hart of PECI focused on presenting some ways that controls are used in buildings. Ventilation is a code-regulated requirement for buildings that is a major source of energy usage. Before major advances in ventilation controls, it was common to provide enough outside air to satisfy the ventilation requirements of the maximum occupancy of any zone. With demand controlled ventilation, DCV, controls can enable air handling units to provide ventilation proportional to the actual occupancy of any zone by monitoring CO2 levels. This is ideal for large areas with high variance in the number of people utilizing the space, like school gyms. Reid wanted us to remember that CO2 is not a contaminant; it is a proxy we use to determine how many people are in a zone.
From there, Reid moved on to discuss Energy Information Systems and Integrated Controls. Energy Information Systems, EIS, allow for energy tracking and immediate feedback of systems in a building. The EIS do not save energy directly, but by helping to inform decision makers, engage and educate occupants, provide trend data, and allow for quick and easy identification of trouble spots, Energy Information Systems can lead to significant energy savings in many cases.
Reid also touched on the benefits of existing building commissioning. He explained that often, systems are not fully functional at the time of initial occupancy and that often, current uses are different than the original design. Reid recommends analyzing the sequence of operations and the points list as well as checking and calibrating sensors in order to retro-commission existing buildings. See His Presentation
Scott Hanken of Abacus Resource Management Company discussed some of the main issues about which building owners and operators should be aware when they are considering the installation or upgrade of a DDC system. Scott explained how the sequence of operations should be written with input from all parties so that there is consensus on the intended results and how they will be achieved. Scott argued that the points list should remain flexible during the planning process because the sequence of operations will dictate the point needed.
Scott talked about typical cost cutting techniques in a retrofit. It is often okay for contractors to reuse existing wire; however contractors should not reuse existing sensors or actuators. Before reusing existing wire, compatibility and network speed must be evaluated. In many cases a retrofit kit for a valve is the same price as a new valve, so replacement makes more sense than retrofit. Scott discussed retrofit techniques for Variable Air Volume (VAV) terminal units (TUs), sensors, and thermostats, including the recommendation that building owners should pay a little more for packaged VAV boxes with factory installed sensors as they are typically more reliable. Scott finished his presentation with a discussion of the typical cost of installing different types of DDC systems, which is useful for making initial estimates or checking contractor prices. See His Presentation
Mark Kinzer, also of Abacus Resource Management Company, and Jack Bickford of Northwest Controls Company presented a case study of their project at the Portland Art Museum. Mark shared how the project developed, from early conversations with the museum director, to the initial scoping report where issues were identified, to the full energy analysis with data logging, to the installation of energy savings measures and the verification of the energy savings.
Some of the major issues that were identified and corrected were: the pumps were very oversized, the chiller was operating 24 hours per day, the VAV boxes were operating as constant flow, and the water side economizer was not operational. Jack was personally responsible for identifying a valve in the wrong position that was preventing water from getting to the waterside economizer, which had prevented this energy efficient feature of the original construction from ever working – after it was fixed the chillers were allowed to turn off about 3,000 hours per year. Mark described the solutions to these problems and how the upgrades were installed. This engaging presentation led to a lively discussion between the presenter and attendees. See Mark's Presentation
Sean Henry of the Oregon Department of Energy (ODOE) gave a legislative update on tax credits available to businesses for energy saving upgrades. Sean talked about House Bill 3680, the bill that replaced the Business Energy Tax Credit with the new energy incentive program for businesses. Sean informed the audience about the most important parts of the new legislation like the new fees, the competitive application process, and the automatic qualification of small projects under $20,000, and the timeline for when the large projects can be submitted to ODOE for review. To find more information, Sean recommends visiting the Oregon Department of Energy website where you read the new rules and sign up to receive “BETC Email Updates.” See His Presentation
David Jackson presented an update on behalf of the Energy Trust of Oregon about the current incentive available for DDC upgrades. Incentives are available for most controls upgrades that incorporate energy saving strategies in existing commercial buildings.