Class A office building system design: Automation and controls
Class A office buildings are among the toughest projects an engineer can work on—complex structures, demanding clients, and advanced technology. Building automation and controls keep these buildings running smoothly.
Daniel G. Dowell, VP Energy Performance Contracting Sales, ABM, Raleigh-Durham, N.C.
Kurt Karnatz, PE, CEM, HBDP, HFDP, LEED AP, President, ESD, Chicago
Lance Kempf, PE, Director of Mechanical and Electrical Engineering, LEO A DALY, Minneapolis
Brian Michelson, PE, MEP Design Phase Manager, Mortenson Construction, Minneapolis
Joseph H. Talbert, PE, ARM, Project Manager, Aon Fire Protection Engineering, Lincolnshire, Ill.
CSE: When working on monitoring and control systems in Class A office building structures, what factors do you consider?
Michelson: I like to make sure that all of the control devices are present to achieve the described sequences of control. In some cases, the system has to be able to interface with other building systems. In high-rise applications, the HVAC system is often integrated as part of the smoke-management system. In this case, the ability of the HVAC control system and the fire alarm system to work together is critical.
Kempf: We consider how the needs and requirements of the tenants compare or contrast to the established build-out guidelines of the building owner or manager; how to address the needs and desires of the tenants while designing systems that do not exceed allotted budgets or conflict with the operability or functionality of the building's core systems; and how to provide the best value for both the owner and tenants with regard to comfort, safety, reliability, efficiency, and predictability.
CSE: What types of cutting-edge sensors, biometrics, or other controls are you specifying in Class A office building projects?
Kempf: We are specifying heat-recovery systems and controls (air, water, refrigeration), occupancy sensors integrated into the control of lighting and HVAC systems, demand-based ventilation systems, and controls that optimize outside-air-ventilation distribution from core building systems. We also are looking at real-time and historical trending of data generated by building automation systems (BAS) and controls to measure system parameters and create dynamic plans to reduce energy usage, minimize waste, and optimize tenant comfort. This is intended to reduce operating costs for building owners and tenants as well as create environments that can be modified or adjusted continuously to increase worker comfort and productivity.
Michelson: Carbon dioxide (CO2) sensors, airflow-measuring stations, and utility submeters are the most common. CO2 sensors and airflow-measuring stations are vital to ensure compliance with ASHRAE Standard 62.1: Ventilation for Acceptable Indoor Air Quality and still allow for reducing system energy consumption. Building owners who are leasing space to tenants are requesting the submeters to monitor energy use and apportion the base building-system operating costs to the tenant.
CSE: What are some common problems you encounter with building automation systems (BAS) in Class A office building projects?
Michelson: Incomplete or incorrect programming that doesn't show up until extreme seasonal conditions are encountered. Control systems that respond too fast or too slow that end up reducing comfort or increase wear on equipment. Another issue that shows up during design and sometimes post-construction is the demand from clients that the BAS be able to control the internal workings of equipment such as boilers and chillers.
Kempf: We have encountered central building controls and control systems that focus inward on core building systems and do not include scalable provisions for monitoring, tracking, and trending the usage patterns or needs of the tenants. We also have seen buildings that are 15 or more years old that retain systems, system components, system controls, and operating procedures that are outdated, inefficient, or inflexible. This is a challenge to engineers and designers who are asked to provide design solutions for tenants or building owners and operators with a new focus on sustainability, flexibility, and efficiency.
CSE: What types of system integration and/or interoperability issues have you overcome, and how did you do so?
Michelson: One of the biggest challenges I faced was during the early days of BACnet when a client requested that every point seen on the chiller control panel be passed through to the BAS. Getting the chiller and BAS to achieve this required a special converter box and additional programming to map those points through. It wasn't completely successful, but most clients don't expect to see bearing temperatures and refrigerant pressures remotely through the BAS.
CSE: What unique tools are Class A office building owners including in their automation and controls systems?
Michelson: I don't know if it's unique, but a lot of owners are looking at ways to shift energy and utility costs to tenants. This has resulted in requests for submetering at tenant electrical panels, domestic water and gas submetering, and even Btu meters for heating water and chilled water. Another challenge is sending building systems into occupied mode for those tenants that have employees working late or coming in on weekends.
CSE: How do you meter or submeter the various portions of the building, such as a restaurant, fitness area, different office suites, etc.?
Kempf: All core building systems (air, water, heating, cooling, power, etc.) can be isolated, metered, tracked, and trended through the thoughtful application of current sensor and system technology. This is often made difficult due to both outdated approaches to distribution of core building services in existing office buildings and the ongoing changes associated with tenants and occupancies.
Michelson: Ideally, system selections for those locations should be set up to operate independently of the base building system so that only the utility connections need to be submetered. Btu meters may be called for in cases where chilled water and heating water are supplied from a central location. However, requiring a large central plant to operate during retail or restaurant hours of operation is not practical.