Updating Energy Performance in Existing Building Stock
In the Pacific Northwest, we’ve been spoiled with abundant and relatively cheap energy. This allowed us to become lackadaisical about our buildings’ energy consumption over the past several decades.
Now, with rising energy prices and climate change concerns, building performance has jumped to the top of our aging buildings’ to-do list.
With active coal plants in Boardman, Ore. and Centralia, Wash., the Pacific Northwest’s clean power reputation is partly a myth. Oregonians still get around 40% of their electricity from coal and only 40% from hydro. Washington utility customers’ electricity is slightly cleaner with only about 17% from coal and 65% hydro. Wind power has seen a great surge in the last five years in Eastern Oregon and Washington but still represents less than 10% of our electricity.
Before you can act responsibly and effectively to improve building performance, it’s important to assess current consumption. Start with a careful review of utility bills and metering logs for the past several years. This may lead to the realization, especially on a campus, that individual building metering is missing and should be addressed as part of the retrofit process. Next, check out the EPA’s Target Finder or 2003 CBEC’s data at www.energystar.gov to see how your building’s Energy Use Intensity stacks up against others in its building type classification.
The first hurdle after deciding to take action to improve your building(s) performance is finding the funds for upgrades. Most northwest utilities have incentive and loan programs for their customers. Their programs vary widely from limited per fixture lighting upgrade cash incentives to Energy Trust’s expansive support system covering everything from HVAC upgrades to commissioning. Incentives, even at the high end, will likely only cover a fraction of actual upgrade costs. If traditional loans seem too much to take on, you may be a good candidate for an energy service company lease. ESCOs oversee and implement the entire upgrade process at no cost to the owner of the project. This creative financing model uses the savings generated by the project to pay for itself. Any additional monetary utility savings is split between the ESCO and the building owner by percentages contractually agreed to by both parties.
Diagnosis and Planning
The only thing existing buildings have in common is that each is unique. For every retrofit project, there is a fabric of systems that have evolved over time to create a particular building. The complete story behind each building’s energy use may be buried in walls, roofs and antiquated mechanical and electrical systems. A team of experts, including architects, engineers and operators, is essential to deciphering existing conditions and recommending effective building performance improvements.
Retro-commissioning is a thorough tune-up of an existing building's systems. To maximize energy efficiency, this whole building review should be scheduled at regular intervals. Some building owners are finding that even yearly reviews will pay for themselves in utility bill savings. The wasteful truth is that the majority of existing building stock has never been recommissioned. The scope of this building check-up typically includes insuring that systems are running as designed and that settings are optimized to reflect actual usage and occupant expectations.
Lighting is the low hanging fruit of energy efficiency upgrades. It is easy to grasp scope requirements and most local utilities offer direct per fixture incentive money. Incandescent and older T12 fluorescent fixtures are very wasteful. Comparing existing light fixtures with new more efficient options and a more modern understanding of adequate lighting levels may even lead to elimination of a number of fixtures as well as better performing lamps such as T8 and T5 fluorescents. LEDs are promising but require more development before they will fully live up to their hype. Controls and daylighting strategies should also be evaluated as the addition of some simple sensors can save you from running lights when there is adequate daylight or no occupants in the space.
Older buildings have notoriously leaky shells often including single glazing, thermal bridges, and inadequate insulation. These envelope issues account for a lot of energy literally leaking out of buildings and their owners' pocketbooks. Unfortunately, it can also be one of the most expensive line items in your retrofit budget. The most effective way to squeeze it into the budget is to assess it as part of the complete upgrade picture; Improving the shell may directly reduce the size of expensive mechanical equipment needed to heat and cool the building.
Mechanical System Upgrades
Mechanical systems should be the last item addressed in a building retrofit as the efficiencies gained by earlier measures often allow much smaller HVAC systems to be utilized. Pairing the cost of reduced mechanical system needs with envelope upgrades can make the difference between unacceptable payback periods and reasonable returns. Sometimes parts of the existing mechanical system, like ductwork, can be reused with modern economizing equipment that separates heating and cooling streams. Other times, a complete rethinking of the conditioning system installed will make sense for the sheer magnitude of energy savings achievable.
Monitoring and Maintenance
A recent improvement to existing building performance is increased emphasis on monitoring and tuning structures to ensure continued peak performance. Now you can know exactly how much energy each building is using annually, monthly and even at any particular moment. Sub-metering can break down that usage into obvious categories like lighting, mechanical systems and plug loads as well as by tenant or use areas. The nonprofit New Buildings Institute is working on an "energy signature" tool to make this abundance of information readily understandable. Water and energy monitoring kiosks integrated into building lobbies and web-based dashboards giving immediate usage feedback can influence building user behavior by directly reporting the impacts of occupant behavior.
Optimizing the energy performance of our existing buildings is the most overlooked and important piece of getting our region's building energy consumption and utility bills under control. Ideally, all buildings should be in a continuous loop of review and tuning; saving the planet and your pocketbook takes vigilance.
ResourcesNorthwest Energy Efficiency Alliance's website to aid business professionals understand the power of energy efficiency in their buildings, www.betterbricks.com
New Buildings Institutes, nonprofit focused on research and tools for energy efficient commercial buildings, www.newbuildings.org
The 2030 Blueprint: Solving Climate Change Saves Billions, Edward Mazaria, Executive Director & Kristina Kershner, Director, 2030, Inc / Architecture 2030, http://www.architecture2030.org/pdfs/2030Blueprint.pdf
Energy Star Building Upgrade Manual, 2008 Edition, U.S. Environmental Protection Agency, http://www.energystar.gov/ia/business/EPA_BUM_Full.pdf
Best Practices in Commissioning Existing Buildings, The Building Commissioning Association, http://www.bcxa.org/downloads/bca-ebcx-best-practices.pdf