Government building design: Sustainability and energy efficiency
When your client is the government, engineering design can be tricky, thanks to stepped-up regulations, budgetary concerns, and other considerations. Respondents discuss sustainability and energy efficiency in government, state, municipal, federal, and military facilities.
- Ian Bost, PE, LEED AP, Principal, Mechanical Engineer Baird, Hampton & Brown Inc., Fort Worth, Texas
- Robert Eichelman, PE, LEED AP, Technical Director, EYP Architecture & Engineering, Albany, N.Y.
- Paul W. Johnson, PE, LEEP AP BD+C, Vice President of Mechanical Engineering, Wood Harbinger, Bellevue, Wash.
- Katie McGimpsey, PE, LEED AP, Principal, Affiliated Engineers Inc., Rockville, Md.
- R. Scott Pegler, PE, LEED AP, Director of Mechanical Engineering, Setty, Fairfax, Va.
CSE: Energy efficiency and sustainability are often the No. 1 request from building owners during new building design. What net-zero energy projects have you recently worked on?
Johnson: None, but would love to have the opportunity. Net-zero projects have significant price points that most owners don't want to cover.
Pegler: Our team was recently involved in a design, which was not carried through to construction, that involved using wood debris (chips) from local citywide pruning operations to supply a biomass thermal oil heater, which in turn was used to power an organic Rankine cycle (ORC) turbine that produced electrical power for the building.
Excess heat from the ORC was used to power an adsorption chiller for cooling or for direct hydronic heating.
CSE: Many aspects of structure sustainability (power, HVAC, maintenance, etc.) require building personnel to follow certain practices to be effective. What, if anything, can you as an engineer do to help increase chances of success in this area?
Pegler: Author sequences that are clear regardless of how sophisticated the equipment may be. Design, in our control systems, appropriate trending, alarming, and graphics that convey clearly systems' intended operation. Involve ourselves during training of operations and maintenance (O&M) personnel to assist in any areas that may be unclear or require additional clarity.
McGimpsey: The building will only operate efficiently if the equipment is maintained and the control sequences are followed. It is important to engage the stakeholders throughout the design process and educate them along the way. System training prior to substantial completion presents a great opportunity to review the overall design intent with the building personnel. Also, engaging the owner 1 year after occupancy and reviewing the energy data to see if the projected energy targets are being met will assist in determining if some system fine-tuning is required.
Eichelman: There are a number of steps that engineers can take during the design process to increase the likelihood that systems will continue to operate at the efficiency levels to which they were designed. One is to keep the systems as simple as possible and to introduce complexity only where it cannot be avoided. A system that is simple to understand and operate has a much better chance of operating properly over the life of the facility versus one that is overly complex, requiring specialized personnel and high levels of ongoing and costly vendor support. A monitoring system should also be specified to allow the owner to understand system status and alarms, as well as the energy consumption and efficiency at selected points and how these compare to expected conditions. Data should be logged for analysis and trending purposes.
Systems should also be thoroughly commissioned following the initial construction, with direct feedback from the commissioning agent (CxA) to the owner and engineer as to how the system efficiencies can be further optimized. Ongoing reviews by the CxA or the engineer should be performed periodically after construction to ensure the systems continue to operate properly. The design should also specify the proper level of training for operations staff to ensure complete understanding of how the systems need to be operated and maintained.
Johnson: Providing space for maintenance access, providing the best controls so that monitoring and alarms are easily observed and reported, and providing effective training as well as accessible and user-friendly O&M documentation for better systems understanding and optimized operations throughout the life of the facility.
Bost: Involvement with the owner and their personnel can provide better education of the design intentions. We do not have much interface with actual building users, and it can be difficult to break old habits.
CSE: Describe any experience you have using sustainable heating/cooling tech, such as geothermal systems.
Johnson: We are currently designing a geothermal heat pump system with a condensing gas boiler backup for an elementary school, targeting an energy use intensity (EUI) of around 20. The system uses a dedicated outdoor air system (DOAS)with heat recovery supplied directly to each heat pump, and individual water-to-air heat pumps serving separate zones.
McGimpsey: I was the MEP project manager and lead mechanical engineer on the National Institutes of Health Porter Neuroscience Research Center Phase II project, which has a geothermal ground source heat pump system. The 60-ton closed-loop system consists of six 1,500-ft deep wells that supplement the processed cooling/heating chilled beam loop. The piping from the wells collects in a common valve vault on-site.
CSE: Please describe your experience with high-performance building projects in government or military buildings.
Bost: The two county sub-courthouses were very educational for all parties. These were the first LEED projects for most members of the team-architect, engineer, owner, and contractors. There was a learning curve, a few minor stumbles, and eventually success.Once the initial steps were hurdled, it became a team effort with good results.
McGimpsey: High-performance buildings and sustainable design must be a priority. We are designing 50-year-old buildings for our government and/or military clients.
Benchmarking similar-type buildings assists in establishing a building EUI. LCCA is an early study that discusses alternative methods of energy conservation and/or energy recovery with the associated advantages, disadvantages, and payback calculations, including utility rebates. Continual energy model updates help educate engineering system decisions throughout the design process to ensure the project is on track to meet the sustainable goals.