- State and federal mandates are driving the adoption of zero energy buildings.
- Develop load reduction strategies first, then energy efficiency features and last renewables.
- Several calculators are available for estimating solar energy and zero energy feasibility.
- Zero energy design for all new buildings by 2020
- 1 percent of all existing buildings must achieve zero energy, waste or water by 2025.
- Zero water or waste design for all new buildings by 2030.
A panel of experts from Seventhwave, a nonprofit providing energy solutions, and the National Renewable Energy Laboratory (NREL) provided their tips for successfully designing a ZEB:
- Benchmark the building's goals by comparing to existing buildings
- Leverage energy modeling early and often
- Include a continuous value engineering process as part of the integrated design effort
- Integrate experienced subcontractors early in the design process
- Develop load reduction strategies first, such as adding insulation, then energy efficiency features
- Add renewable energy last; typically 75 percent of the roof area should have solar panels
- Design roofs to be solar ready; relocate HVAC (vent drains)
- Take advantage of other features to increase solar capacity, such as overhangs or drive-thru roofs
- Include best-in-class energy efficiency requirements in equipment procurement specifications
- Allow cost tradeoffs across disciplines
- Optimize window area for daylighting (window-to-wall ratio = 30 percent)
- Maximize use of modular and repeatable high efficiency design strategies
- Leverage value-added benefits to efficiency strategies and consider life cycle cost benefits
- Integrate simple and passive efficiency strategies with the architecture and envelope
- Think early on how to mitigate uncertainty regarding building operation
- Keep systems as simple as possible so they're easy for occupants to operate
For a campus or portfolio, look at all of the buildings as a collection and consider mass retrofits. Determine where on campus it makes the most sense to locate energy generation equipment.
The NREL offers several tools to help determine you solar energy needs:
- The PVWatts Calculator estimates the performance of potential PV installations, automates solar radiation lookup and provides guidance for efficiency and losses.
- The System Advisor Model makes performance and cost estimates based on system design parameters.
- The Solar Ready Buildings Planning Guide offers advice on solar thermal and photovoltaic systems.
Seventhwave's Back-of-the-Envelope calculator looks at a building as an energy system to help determine how one change affects the energy consumption of the entire building.
The DOE's Building Upgrade Value Calculator converts energy efficiency upgrades into metrics that are easily understood by financial decision makers.
Image source: NREL