COVID Shows That Even Empty Buildings Must Use Energy
In a time when commercial real estate owners face COVID building occupancy challenges, energy efficiency can easily fall low on the to-do list.
Many owners may understandably think that with a portfolio of buildings largely sitting empty, energy costs will drop to all-time lows, so there’s no need to invest in energy efficiency measures (EEMs). After all, with only a few tenants in an office building to occupy plug-loads, switch on lights and crank up the AC, energy costs should be dropping dramatically.
However, an analysis of Carbon Lighthouse clients shows that during shelter in place (SIP), 25% of building energy use did not change. Another 60% of buildings did show energy reduction, but only by an average of 23%, a largely disproportionate percentage compared to the +80% drop in occupancy most are experiencing.
So what is the discrepancy? Let’s take a deeper dive into the relationship between occupancy and energy consumption to answer that question.
Energy Use & Occupancy — It’s Not 1:1
If a building is run exactly the same way without any tenants, it’s likely to still operate at 60% of its normal load (the amount of work a building has to do to deliver the required air temperature and quality).
The graph below shows several scenarios for how a building might operate with occupancy ranging from 0% to 100%.
- Buildings with many windows without blinds, a large, dark roof, and lighting and plug loads that can’t be turned off would be stuck near the maximum load range (near 100% of full load) regardless of occupancy.
- A building that allows for more aggressive efficiency measures — with all window blinds closed, lighting controlled by occupancy or simply turned off, and most or all of the plug loads disconnected — could push toward the minimum load, which is still estimated at around 20% with zero occupancy.
- It’s a widely accepted industry standard that people only contribute around 20% of the heat in a building, so whether or not people are in the building only starts to matter in more efficient buildings.
How could this be? Why can’t load, and subsequent energy costs, be brought down more?
Many operators have their hands tied with lease agreements that require tenant spaces to be operational, regardless of occupancy, at set business hours. If operators fail to meet those requirements, tenants could terminate their lease agreements.
Additionally, many tenants have equipment that must continue to operate for their companies to run, such as servers that control their businesses or allow workers to work remotely with access to email, databases or software tools — and we’ve found that 30-50% of a building’s load is attributed to tenant-driven factors.
Outside of how tenants use energy, it’s important to note that the buildings themselves also use energy to simply maintain functionality. Buildings use energy to ensure that air temperatures and humidity are not only optimized for tenants when they’re in the building, but also for the equipment that’s running in basements or within the walls of the buildings. Doing so can avoid expensive equipment damage or replacement.
All of these uses are then impacted by uncontrollable variables. Outdoor air temperature (OAT) and sunlight are typically the number key drivers of building load and energy variation, accounting for 20-50% of the load depending on location. Especially in the case of a building with a large black roof or a predominantly glass exterior, OAT can have significant ramifications for how a building uses energy to heat and cool itself.
Optimizing Operations For The New Normal
Operators face complex challenges in the “New Normal.” While the current obstacle is running a building amidst low COVID building occupancy, there will be future challenges to overcome; perhaps tenants rearranging their office spaces and using energy differently, scheduling shift work over longer workdays, or moving out altogether, will be common in the months ahead.
No matter the challenge, operators need the right systems and processes in place to help handle shifting and varied occupancy loads as buildings evolve. They would be hard-pressed to do it alone. Operators who tap technology to help them run their buildings will then have the advanced sensors, controls, experts, and solutions needed for longer-term portfolio resilience.
For example, if an office building typically operates using two air-cooled chillers, the building engineer, having spent years operating the building, would likely have the technical expertise and gut feeling to know that they could only run one chiller right now. But implementing that change requires reprogramming sequences, setpoints, and parsing through a daunting amount of interactive and cascading effects that will subsequently occur. This requires advanced visibility into a building management system (BMS) as well as advanced control capabilities.
However, in Carbon Lighthouse’s experience, we found that 15% of buildings don’t have a BMS in place at all and those that do are often lacking controls measures such as variable frequency drives (VFDs). Without VFDs on items such as fans or pumps, engineers can’t tweak how hard equipment works — it’s just an on or off switch.
Carbon Lighthouse built our advanced AI for real estate, called CLUES®, to bring quantitative clarity to this complicated decision making.
Having analyzed over 100 million square feet of commercial real estate, CLUES is a proptech platform with the power to accurately adjust the complex and interdependent configurations of HVAC systems — around the clock, across a variety of ambient and occupancy regimes – so that the building’s energy usage is always optimized for maximum energy efficiency and savings, tenant safety COVID requirements, occupant comfort, and carbon emissions reduction.
Each month CLUES ingests more than 690 million data points from hundreds of sensors at each building, enabling it to capture the performance data of individual systems and understand their relationships at a level far beyond what is possible from analyzing electrical data or data from the BMS only. So, no matter what the “New Normal” looks like, CLUES will be there to adjust and optimize.
Case Study: Manhattan Office Building
Our energy-savings-as-a-service model has already helped several clients better navigate building operations in the midst of COVID. A prominent NY office owner and client who owns more than 13MM sq. ft. of Class A Manhattan office and retail space approached us to help its sustainability and engineering teams understand its building’s energy use. Carbon Lighthouse engineers used CLUES to analyze whole-building power before and after SIP to determine the impact on an office tower in Manhattan’s energy use (see graph below).
The orange line represents energy use prior to SIP based on historical data. The red line represents actual operation (power consumed in kW) after SIP. Our analysis found that overall building energy use only decreased by 26% even with low occupancy.
Further, Carbon Lighthouse used CLUES real estate software to understand how previously implemented EEMs were now performing, particularly while the building was operating under unusual conditions.
For example, earlier this year, we implemented chiller staging adjustments and an upgraded BMS. The graph below compares the building’s energy use between March and June in 2020 versus 2019. Our analysis shows that under similar weather conditions, power use dropped by approximately 50% compared to the previous year, confirming that previously implemented EEMs were still performing well and will achieve the expected results.
This type of granular analysis gave the engineering team invaluable insights into building energy operations monitoring and allowed the sustainability team to accurately report on their key ESG data — while taking a heavy burden off of these teams’ shoulders.
Because buildings have so many factors that make them dynamic — the equipment in them, the people in them and even where they’re located — their energy use was complex even before the COVID building occupancy challenges.
Without Carbon Lighthouse, CRE owners could never obtain, much less analyze, the level of insight CLUES has gleaned from the hundreds of buildings we’ve optimized.
Even with the unusual data, partially loaded buildings, and everything else that comes with COVID’s New Normal, CLUES and our data engineers are ready to bring clarity to your portfolio, with dynamic energy management software that helps achieve cost savings now, while maintaining safety and saving energy into the future.