Specifying energy efficiency systems for new, existing office buildings
Office buildings might seem like simple structures from the outside, but engineers engaged in such projects know they can be highly complex, and building owners are requesting more sustainable buildings.
J. Patrick Banse, PE, LEED AP, Senior mechanical engineer, Smith Seckman Reid, Houston
Robert Ioanna, PE, LEED AP, Vice president, Syska Hennessy Group, New York City
Douglas Lacy, PE, LEED AP BD+C, Senior associate, ccrd partners, Dallas
CSE: What software or systems do you use to model the energy consumption of the building?
Lacy: While we use a variety of modeling software packages, we use Carrier’s Hourly Analysis Program (HAP) for most projects.
CSE: Describe window treatments (glazing, louvers, etc.) you have recently designed.
Lacy: We employ the daylight analysis features in AGI32 to assist our architectural clients in designing or validating the design of various horizontal and vertical louver systems. Once optimized for daylighting we compare to the effect of various glass selections. In some instances we have seen that improved glazing can result in more savings than that offered by louvers, especially when you have a less-than-desirable building orientation due to site conditions.
CSE: When designing the building envelope, what unique techniques or tools have you used?
Ioanna: We are being brought onboard projects much earlier than in previous times in the design of office buildings. Early on, when the basis of design decisions is being made for the architectural systems, we have used COMFEN to analyze alternative fenestration systems. COMFEN contains a sophisticated analysis engine that dynamically simulates the effects of key fenestration variables on energy consumption, peak energy demand, and thermal and visual comfort. The results from the simulations are presented in graphical and tabular format for comparative fenestration design cases to help users move toward optimal fenestration design choices for their project. This has proven to be a cost-friendly alternative approach for building owners to make quick and informed decisions at a somewhat reduced cost.
CSE: How have you worked with the architect, owner, or other players to ensure the building envelope goals are achieved while maintaining aesthetic appeal?
Banse: Working with architects involves discussing glass types, location, required wall and roof insulation, and exterior and interior shading types and benefits at a minimum to achieve energy goals and meet minimum code requirements.
CSE: Describe a recent project in which daylighting played a role in the lighting design of the office building.
Banse: Our own office space uses daylighting for exterior open space and interior offices that adjust and dim lighting to meet design light levels and be a part of achieving LEED Platinum status.
Ioanna: We have found that proper daylighting systems reduce lighting and cooling energy significantly, but the true benefit of daylighting is the positive impact on the occupants. Our current New York headquarters space implemented a daylighting control system. While the energy consumption was reduced based on the design, the overarching success of it comes from employee satisfaction.
CSE: What types of renewable energy systems have you designed for office buildings?
Lacy: While many of our institutional and build-to-suit clients have shown interest in renewable energy system, in a standard office development model the resale time horizon for the building is often shorter than the ROI on the renewable systems and thus renewable energy systems are typically not pursued.
Ioanna: We have designed photovoltaic systems, geothermal heat pump systems, microturbines at steam pressure reducing stations, solar hot water heating systems, and fuel cell systems.