Additional Measures to Reduce Peak Energy and Fossil Fuel Consumption
As shown in Table 4, the City will have to implement other energy reduction measures besides using an ESCO if it does not achieve more than a twenty percent annual penetration rate. RMI analyzed other energy reduction potential opportunities in the City of Cambridge to offer a variety of options as to how to meet the energy reduction goals:
- Enhanced ESCO: This portfolio adds another layer to the traditional ESCO model by including energy reduction measures that a traditional ESCO may not normally use, such as radiant barriers and high performance glazing.
- New construction: This portfolio includes energy reduction measures that have the potential make new residential and commercial construction 20-40 percent more efficient than existing code.
- Institutional: This portfolio includes energy reduction measures for campuses, data centers and labs.
The options reach across three primary building types: residential, commercial and institutional. Below, Table 5 shows the potential peak megawatt reduction associated with the enhanced ESCO and new construction options, at differing penetration rates. RMI was not able to determine the peak energy reduction from the institutional sector, so it is not included here. The peak megawatt reduction potential listed is additional, meaning that the enhanced ESCO reductions do not include the ESCO-only peak megawatt reductions. Similarly, the ESCO-only portfolio does not include new construction.
If the ESCO-only model can only achieve a seven percent annual penetration rate, it can be combined with the enhanced ESCO model for a variety of measures that can be combined at different penetration rates to meet the 50 MW goal. Each of these options, and the energy reduction measures included in it, are discussed in more detail below.
Table 5. Annual Potential Energy Savings from Options
| Enhanced ESCO | |||
|---|---|---|---|
| Existing residential and commercial sector | Penetration rate | Annual peak MW reduction potential | Five-year peak MW reduction potential |
| 7% | 8.4 | 42 | |
| 20% | 24 | 120 | |
| 100% | 120 | 120 | |
| New Construction | |||
| New construction (residential and commercial) | Penetration rate | Annual peak MW reduction potential | Five-year peak MW reduction potential |
| 100% | 5.1 | 5.1 | |
As shown in Table 4, even if the ESCOs-only model achieved a one hundred percent penetration rate in the existing residential and commercial sector the City’s energy reduction goal would not be met. Thus, additional measures need to be taken by the City and the Cambridge Energy Alliance. Below, Table 6 and Table 7 display the measures and the corresponding assumed energy savings for enhanced existing residential and commercial sector retrofits. The measures that are included either impact peak or thermal demands; thus working towards either of the reduction goals. These estimated savings are based on the following assumptions:
- In the residential sector, a seven percent annual penetration rate is assumed,
- In the residential sector, seven percent of the housing stock equates to approximately 3,100 units,
- In the commercial sector, a seven percent annual penetration rate is assumed, and
- In the commercial sector, seven percent of the commercial stock equates to approximately 2,730,000 square feet.
Using these assumptions, RMI analysis indicates that if the City of Cambridge uses an enhanced ESCO model in the existing residential and commercial buildings, there is the potential for approximately 8.2 MW peak load reduction annually. Over five years, this would achieve 42 MW, or 84 percent of the 50 MW goal.
Table 6. Annual Potential Savings from Enhanced Existing Residential Sector Retrofits
| Energy Reduction Measure | Megawatt peak reduction (MW) | 1000 therms/year reduction |
|---|---|---|
| Dispatched Load Shedding | 0.18 | - |
| Radiant barrier paint, blower door testing, attic door sealant | 0.04 | - |
| High performance glazing | 0.43 | - |
| Daylight response dimming sensors | 0.11 | - |
| Comprehensive lighting upgrades | 0.09 | - |
| Simple Daylighting strategies | 0.06 | - |
| Advanced controls | 0.15 | - |
| Replacement program for circulating pumps/thermostatic valves | 0.03 | - |
| Solar Hot Water | - | 43 |
| Boiler/Furnace Replacement (High SEER Rating) | - | 11 |
| Heat Recovery | - | 0.38 |
| Total Annual Reduction |
1.1 |
54 |
Table 7. Potential Savings from Enhanced Existing Commercial Sector Retrofits
| Energy Reduction Measure | Megawatt peak reduction (MW) | 1000 therms/year reduction |
|---|---|---|
| Advanced controls/Demand Control Ventilation | 1.6 | - |
| High-performance glazing | 1.2 | 0.44 |
| Building Management System | 0.49 | - |
| Energy modeling | 0.48 | |
| Submetering | 0.43 | |
| Continuous Commissioning | - | 0.40 |
| Daylighting | 0.31 | - |
| Comprehensive lighting strategies | 0.37 | - |
| Advanced lighting controls | 0.31 | - |
| Measurement and verification | 0.29 | - |
| Automated time of day scheduling | 0.23 | - |
| Replacement program for circulating pumps/thermostatic valves | 0.47 | - |
| Daylight response dimming/photosensors | 0.21 | - |
| Simple daylighting strategies | 0.15 | - |
| Heat recovery | 0.12 | 0.53 |
| Right size cooling | 0.04 | - |
| Marketing and information program for participants | 0.05 | - |
| Window retrofits | 0.05 | - |
| Dispatched load shedding | 0.51 | - |
| Total annual reduction |
7.3 | 1.4 |
In addition to pursing enhanced energy efficiency measures, the City will also need to aggressively pursue efficiency within the new construction sector. Significant gains can be made in new construction due the incredible potential to maximize efficiency at the initial design or construction phase. RMI conducted analysis on the potential impact of efficiency measures within the new construction sector. Given the size and scale of the newly approved NorthPoint development, (2,700 new residential units and over 2.2 million square feet of commercial space) NorthPoint provides an opportunity for the CEA and the City to work with the development team to implement numerous load reduction strategies. By increasing the efficiency of NorthPoint, and other new developments in Cambridge, the measures implemented by the CEA and the ESCO in the existing building sector will have a greater impact.
Below, Table 8 and Table 9 display the measures and the corresponding assumed energy savings for new construction in the residential and commercial sector. These estimated savings are based on the following assumptions:
- In the new construction sector, a 100 percent penetration rate is assumed.16
- NorthPoint has reported a build-out of 2,700 residential units and 2.2 million square feet of commercial space.
Using these assumptions, RMI analysis indicates that if the City of Cambridge requires stringent new construction standards for residential and commercial buildings, approximately 5.1 MW of peak load reduction is achievable on an annual basis. However, it is important to note that as mentioned in the “Load Growth” section, the NorthPoint development is likely going to be the majority of the new construction in the Cambridge area for several years. Thus, it may be overly optimistic to project that the City will be able to achieve 5.1 MW of peak load reduction on an annual basis. However, if the City did, new construction could meet 10 percent of the 50 MW goal annually.
Table 8. Potential Savings from New Residential Construction Efficiency
| Energy Reduction Measure | Megawatt peak reduction (MW) |
|---|---|
| Ultra Efficient House: measures include eliminate heating systems, passive cooling, advanced daylighting controls, Energy Star appliances, variable speed ECM, solar water heating | 1.71 |
| High Efficient House: measures include variable speed fan furnace, passive cooling, advanced daylighting controls, Energy Star appliances, variable speed ECM, solar water heating | 0.97 |
| Occupant training | 0.40 |
| Total annual reduction | 3.1 |
Table 9. Potential Savings from New Commercial Construction Efficiency
| Energy Reduction Measure | Megawatt peak reduction (MW) | 1000 therms/year reduction |
|---|---|---|
| Higher EER-rating equipment | 0.85 | - |
| Improved envelope | 0.38 | 0.86 |
| Advanced daylighting controls | 0.31 | |
| District heating and cooling (CHP) | 0.24 | 1.1 |
| Building Automation system | 0.18 | - |
| Total annual reduction |
1.2 |
2.0 |
There are additional measures that do not contribute to peak load reduction, but do increase the over all efficiency of new residential and commercial buildings, and thus reduce demand that the City should consider when crafting energy codes. Examples include variable speed fans and pumps and passive measures (daylighting, natural ventilation).
Institutional Efficiency and Programs
Pursuing institutional efficiency can offer further reductions in peak load energy use. Strategies discussed in this section would contribute to reduce load growth in the future, as well as reducing the current peak load. Many of the institutional measures discussed here are energy efficiency measures. However, these measures do offer the opportunity to reduce peak load because so many of the institutional energy reduction measures are geared at energy efficiency.
The measures discussed are:
- Co-generation and tri-generation
- HVAC improvements
- Data centers
- Lab buildings
- Behavioral changes
- Water conservation
- Distributed/renewable power generation
In addition to discussing energy reduction measures that will help the City meet it’s energy reduction goals, this section also discusses institutional programs that will also facilitate energy reduction. The institutional programs discussed are:
- Cross pollination
- Carbon offsets program
- Peer-to-peer training program
- Design team incentives
- Building potential rating s Owner services program
Institutional Efficiency Measures
Co-generation and Tri-generation: Energy reduction opportunities through co-generation and tri-generation exist for many types of institutions found in Cambridge, including: universities, hospitals, large apartment buildings, and hotels. Co-and tri-generation have the potential to double the efficiency of the existing prime movers in Cambridge from thirty-five percent efficiency to approximately seventy percent efficiency. The Cambridge Energy Alliance and their ESCO partners could help identify institutions that could take advantage of this opportunity, and address the regulatory challenges that could arise with this technology. Small and large-scale systems in various types of institutions could be sized from 60 kW – 50 MW, and cost roughly $250,000 to $10 million.
HVAC Improvements: Heating, ventilation and air conditioning (HVAC) offers significant energy savings on an institutional level and for the City of Cambridge as a whole. Increasing the efficiency of several components of the HVAC system can result in energy savings of 30-50 percent:
- 15 percent saving from commissioning/retro-commissioning with Demand Control
- Ventilation,
- Two percent savings from free cooling,
- Three percent savings from efficient light fixtures, and
- Reductions in water use
While a 30-50 percent reduction in building energy consumption is a large saving, if these measures are applied in thousands of buildings in the City, the energy savings could begin to approach twenty-five percent of Cambridge’s total energy use.
Commissioning: In terms of commissioning at a campus level, a range of four steps to present more options for institutions is given. They recognize the different entry levels that each may have.
- Controls: The implementation and correct calibration of controls can make existing building systems perform to their fullest potential.
- Retro - Commissioning: Retro or re-commissioning would identify opportunities for improvement, above and beyond just controls adjustments.
- Continuous Commissioning: Constant monitoring of buildings and their systems would ensure the most efficient operation over the life of the building.
- LEED for Existing Buildings: An institution could require every existing building to go through the LEED for Existing Buildings Certification process. A minimum level of achievement could be mandated, as well as requiring the completion of optional LEED-EB credits, thus making certain steps mandatory.
Data Centers: In the next ten years, Cambridge could easily expect to see a 10 – 50 MW of peak power demand increase caused by data centers. With proper design and smart choices in computing equipment, 50 percent of that energy could be saved (in cooling and computing energy). This could result in a peak demand reduction upwards of 12 MW after a growth of 24 MW of peak power demand.
Lab Buildings: Harvard cited that out of a stock of 600 buildings, 30 large lab buildings account for 40 percent of Harvard’s greenhouse gas emissions, which has a direct correlation with energy use. Improvements and renovations to lab buildings and their operations could save significant amount of energy. This could be accomplished by installing low flow hoods, initializing night time setbacks, demand controlled ventilation/reductions in air changes per hour, and by changing behavior to reduce the increased airflows designed in for unnecessary safety measures. This strategy may also require a change in lab design airflow standards.
Behavioral Changes: If universities or other institutions are able to encourage the identification of “phantom loads” in campus buildings and residences, they may use the findings to encourage behavioral change (i.e. using power strips and turning the entire power strip off). Also, other institutions and the City of Cambridge could build off of the recent Harvard success of realizing a 10 – 15 percent reduction in electricity use can be achieved in dorms through a social marketing campaign.
Water Conservation: Reducing water use also presents an opportunity for energy reductions because of the embodied energy in every drop of water used in the City, particularly because the Walter J. Sullivan Water Treatment Facility for the City is the single largest energy user. For example, a 30 percent energy reduction can be achieved by replacing all water fixtures with low flow equipment. Institutions in Cambridge currently use 19 percent of the City’s water, thus, efficiency from this sector along could result in a six percent reduction in total water use. The energy savings associated with this volume of water efficiency is approximately 600 MWh.
Distributed Generation and Renewable Power Generation: Distributed generation and renewable power generation offer the universities in Cambridge the ability to avoid building a new campus central plant, which would ultimately lead to peak reductions, as well as considerable energy savings at all times.
Institutional Programs
Though the following programs can less be analyzed for impact at this time, their effect on the reduction of energy use for institutions should not be ignored. These ideas represent more ways for institutions to operate more efficiently and improve their sustainability efforts.
Cross Pollination: The Cambridge Energy Alliance could identify opportunities in institutions with a more developed energy reduction plan, and create a “cross pollinator” position to help other institutions benefit from the knowledge gained at institutions further along in the process.
Carbon Offsets Program: The more developed institution could fund another institution’s energy savings measures through interest free financing, which would reduce emissions for the institution granted the funding, and allow the giving institution to claim the CO2 assets.
Peer-to-peer Training Model: Similar professionals within institutions can hold workshops that allow attendees to share knowledge of a certain profession as it pertains to the institution. This creates content experts out of all attendees. Though this model requires a sizeable investment, the returns are also significant. This model can also be extrapolated to the Cambridge community at large.
Design Team Incentives: Performance and integration based incentives could ensure that the project design teams develop the most efficient design and that actual building resource use is measured after occupation. The incentive would be in the form of fees paid out depending on how well the building performs.
Building Potential Rating System: Valuing the existing building stock potential to save energy may help campuses capitalize on energy savings to be had. A rating system could be created, which values the potential savings, so that the least efficient building would be rated the highest. Identifying “resource mines” in this way can have a variety of benefits, such as inciting student competition, creating a marketing opportunity, and helping ESCOs in choosing potential projects.
Owner Services Program: To ensure a smooth transition between construction, commissioning and owner occupation, a process could be implemented to assist in handing off the building to its end users. This way the operations managers can be fully educated on how the building is intended to operate.
With improved operations and the implementation of programs that support efficiency at various institutions and institutional levels, resource savings can happen dramatically, quickly, and be of a great magnitude.
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AIRxpert Systems has developed a unique and flexible indoor air monitoring and control system that is specifically designed to enable managers of of large, existing buildings to cost-effectively implement demand control ventilation (DCV). The system can even be rented, vs. purchased, in order to perform initial diagnostic evaluation (and adjustment) of an existing HVAC system. Numerous local customers (BID Medical Center, MIT, Boston Properties, Boston Public Schools) have rented and/or purchased this system and found it to be extremely valuable. This initiative should evaluate this solution as well. The website is http://www.airxpert.com.