Energy retrofitting means including energy-efficiency processes in all building upgrades, renovations and repair activities related to a building’s energy-consuming systems. Systems may include the building envelope, heating, ventilating and air-conditioning, automation, lighting and roofing systems.
When chartering energy retrofit projects for existing buildings, it is assumed that the operating team has a sound understanding of the building’s mechanical and electrical systems, as well as mechanical, electrical and plumbing systems interactions, overall energy performance characteristics and maintenance histories.
One of the first tasks is to retrocommission the MEP systems of a building in order to meet the design specifications and performance expectations of the original design team and to improve how building systems function together. This process not only creates a baseline for performance, but also allows for a more accurate payback analysis of system retrofits based on energy savings. The team will develop an understanding of individual system component performance and the performance impact to the whole system. Depending on the age of the building, sometimes it is helpful to consult with the original design consultants to understand the basis of design.
Our company also mandates annual Energy Star benchmarking using the Environmental Protection Agency’s Energy Star Portfolio Manager benchmarking tool to allow the team to better understand how the building is performing when compared to similar buildings nationwide. Energy-use intensity results will be reflected in thousand British thermal units, kBtu, per occupied square foot. The smaller the value, the better.
There are two types of energy retrofits:
• Conventional energy retrofits. Conventional energy retrofits are system modifications that focus on isolated system upgrades and a quick payback (typically less than three years) such as retro commissioning, HVAC system upgrades, building automation system upgrades and lighting system upgrades.
• Deep-energy retrofits. A deep energy retrofit achieves greater energy savings by using a more holistic, design-centered approach. These projects are more extensive and involve significant overhauls or replacements of building systems.
A key step to chartering energy projects is an integrated team charrette where key stakeholders and experts are involved in an informative workshop to create realistic and achievable energy goals and objectives based on the building’s life cycle and the individual energy project’s life-cycle cost analysis. Stakeholders may include the following individuals or disciplines:
• Building management
• Building engineers
• MEP engineers
• Structural engineer
• Utility representative
• Automation contractor
• Fire alarm contractor (Important to include this group when developing scope for chiller retrofits related to refrigerant release detection and monitoring and BAS upgrades related to smoke control.)
Discussion points for the workshop may include:
• Three-, five- and 10-year capital plans.
• Ownership energy and sustainability initiatives.
• Ownership anticipated investment term and return on investment expectations.
• MEP systems that are facing impending failures, at or near the end of their useful life expectancy, or where parts are becoming obsolete and hard to find.
• Utility incentives.
• The building’s energy consumption trends and benchmark data.
• Analyze energy and cost economics.
• Individual project prioritization and integration.
• Lessons learned from past projects.
Once the team has clearly defined the projects, four important process groups need to be considered to ensure that the project meets its performance and energy goals.
1. Plan. At the onset of a potential project, it is important to gather input from all key stakeholders to determine existing capital plans in place, challenges faced by operations and maintenance staff, and related building concerns such as comfort and indoor air quality.
The energy use should be benchmarked and analyzed early in the process to determine the potential energy-savings opportunities. An initial energy assessment will identify potential opportunities, including the energy savings and cost expectations. Goal setting in this phase will help prioritize opportunities and focus the remaining phases of the project.
2. Design. To finalize the scope of the energy-upgrade project, detailed energy savings and cost estimates should be performed to confirm the project budget and the expected economics. For large upgrades, a computer-simulated energy model can be used to capture interactions between various systems. An integrated design process is key to pull together information from team members such as a contractor to confirm the budget and the commissioning agent to begin reviewing the system design. Having licensed professionals design and engineer system upgrades is important to capture the whole system picture and implement the best long-term strategy.
3. Implement. Once the project is developed and financing is in place, implementation of changes can begin. Modifications may occur in one upgrade or in multiple phases. Commissioning should be included in this process to coordinate across contractors, review submittals, perform site observations, test equipment operation and monitor operation. Any necessary metering upgrades should be installed at this time along with integration of the building automation system with monitoring software to set the stage for ongoing optimization.
4. Performance. With an integrated design process, well-coordinated implementation and thorough commissioning, the upgraded building will be ready for ongoing high performance. To help confirm and maintain this performance, ongoing commissioning and monitoring should be incorporated. If the BAS has been integrated with monitoring software during commissioning, ongoing commissioning can be cost-effectively executed over the first year of operation to confirm operation during changing weather and occupancy conditions.
Energy consumption also should be monitored throughout the year using demand interval data to evaluate the energy use post upgrade. At the end of the first year, the energy savings can be documented and a new baseline set for comparison in future years. Throughout operation, executing a proactive maintenance plan will help ensure the building stays on track with project goals.