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Rise of the Hybrid Workplace

Office InteriorThe pandemic provided companies with an unprecedented opportunity to rethink the fundamentals of their physical workplaces. Many learned that employees are just as productive when working remotely, and employees overwhelmingly want the option to work remotely at least some of the time per a CBRE study [PDF]. While no one can predict the future with certainty, there are strong indications that a hybrid workplace – a mix of in-office and remote work – will be widely adopted in New York City’s commercial office sector once most employees return to the office. In fact, three Class A building owners interviewed for this project view hybrid workplaces as a likely outcome following the pandemic, while four tenants confirmed they are likely to adopt some form of hybrid workplaces themselves. Within this context, how can we match energy consumption with fluctuating office occupancy?

Saving Energy in the Hybrid Workplace 

Conversations with engineers, architects, and consultants highlighted three basic strategies to tailor energy use to the hybrid workplace conditions of reduced and fluctuating occupancy. We will call these strategies “people counting,” “people clustering”, and the “3 or 4-day in-office workweek.” Purely from an energy-saving perspective, the 3 or 4-day in-office workweek clearly stands out for its simplicity and for the strong likelihood it will produce significant whole-building energy savings. These strategies are described below. 

Strategy 1: People Counting

The “People-Counting” strategy relies on people-counting devices and integration of occupancy data with HVAC controls to match delivery of HVAC service to the number of occupants on the premises in real time. 


1. No Behavior Change Required

This strategy does not require convincing employers and employees to change the way they use their offices, and it does not depend on close coordination among facility managers, IT managers, and program managers for its effectiveness. 

2. Already Exists in Limited and Specialized Applications

As mentioned during an ASHRAE webinar Link opens in new window - close new window to return to this page., the Rudin organization uses real-time data from card key swipes at turnstiles to determine how many occupants are on the floors of each of its office buildings. When turnstiles detect lower occupancy on specific office floors, the proprietary Prescriptive Data software deployed by the Rudin organization reduces HVAC system fan speeds on those floors. 

3. People-Counting Devices Already Exist

There are several other direct people-counting methods including seat sensors, plug load monitors, logins to a Local Area Network (LAN), security cameras, and beacon technology that can detect the number of people in a building via their cellphones. There are also indirect people-counting devices including CO2 sensors and thermostats. 

4. Costs Can be Spread Broadly

The costs of installing and maintaining people-counting devices need not be recouped solely from energy savings from HVAC, lighting, and plug loads. Rather, these costs can be spread over all occupancy-driven office services, including office cleaning, printing and copying, and employee amenities such as coffee service.


1. Lack of Systems Integration

While several people-counting technologies exist and more are coming, the flood of data they produce is not actionable unless analyzed and integrated with HVAC control systems, either at the building (BMS) level or at the floor-by-floor HVAC distribution (VAV box) level. Until there is a full-fledged master systems integration, data from people-counting devices will need to be analyzed separately and then manually integrated with HVAC controls. This, in turn, could necessitate third-party analytics support and/or additional in-house staffing.

2. Complexity

There is already considerable difficulty and expense in programming, reprogramming, maintaining, and retro-commissioning complex HVAC control sequences. Adding occupancy data from people-counting devices may overwhelm HVAC controls. In recognition of this challenge, two high-level executives from a major HVAC controls manufacturer believe creating HVAC controls that respond dynamically to occupancy levels will be a prime focus of R&D efforts going forward. 

3. Elusive Business Case

Installing occupancy-based management systems for HVAC requires substantial upfront investment, as well a commitment to incurring substantial ongoing costs to develop the third-party data analytics capacity and the in-house analytics staff capability needed to operate them. Many building managers and tenant facility managers are looking for quick payback periods, and since people-counting strategies are mainly untested, it’s hard to develop data to justify their costs. 

Strategy 2: People Clustering

People-clustering is a type of smart space utilization that relies on behavioral changes to cluster employees who are in the office into the fewest HVAC zones practicable, leaving the remaining HVAC zones unoccupied so that HVAC service and lighting can be turned off. 


1. Occupied Areas and Employees Who Will Occupy Them are Assignable 

A key feature of the people-clustering strategy is that managers can plan and assign which HVAC zones in a hybrid workplace will be occupied, and which employees and/or groups of employees will work within the HVAC zones on any given day. Within each occupied HVAC zone, seats will be allocated via hoteling (seats can be booked in advance) or hot-desking (first come, first served). 

2. Technology Needed is Simple and Available

No new and untested hardware is needed to execute the people-clustering strategy for HVAC – just simple occupancy sensors already in widespread use to turn off overhead lighting and HVAC in unoccupied areas.. Also, there is no need to integrate building and IT systems that are not capable of being integrated.

3. People-Clustering is a Low-Cost Strategy 

In addition to being low-tech, people-clustering is also relatively low-cost. The only upfront investment is in maximizing the number of HVAC zones on each floor that are individually controlled by equipping as many as possible with thermostats and vacancy sensors. 

4. Software and Mobile Apps Will Make People-Clustering Easier

Software for employers and mobile apps for employees either already exist or are on the way to help facilitate people-clustering. For example, hoteling software already exists that allows employees to reserve their desks and to preview their workspace to see where they will be sitting in relation to colleagues. 

5. Clustering is Already Being Used for After-Hours HVAC

Some tenants have already adopted a practice of people-clustering or “grouping” employees working evenings or weekends onto a single floor or within a portion of a floor served by a single air-handling unit. This strategy enables tenants to use less high-priced after-hours HVAC to support extended operating hours. Check out this White & Case success story that highlights how the law firm strategically placed their staff to optimize after-hours energy use. 


1. Individual Controls for Every HVAC Zone May Not Pay Back Fast Enough

The people-clustering strategy will work better – and will have more granularity and flexibility -- if the number of individually controlled HVAC zones on each floor is maximized. In many existing offices, one thermostat controls multiple HVAC zones, which requires a retrofit of tenant spaces. Engineers interviewed are not sure whether the people-clustering strategy will save enough electricity to justify retrofitting HVAC zones with individual controls for all existing tenants, although this strategy could be cost effective for new tenant fit-outs. 

2. Clustering Requires Complex Coordination and Possible Culture Change

Determining which HVAC zones should be occupied and unoccupied each day and allocating seating areas for each day’s in-office employees will require close coordination among facilities managers, energy managers, IT managers, project managers, department heads, and HR. Furthermore, a transition to hoteling or hot-desking may require long-term engagement by managers to generate employee buy-in. In short, managing a people-clustering strategy may be more feasible for large tenants with robust corporate real estate and facilities management staff, while smaller tenants may simply lack the bandwidth to successfully implement clustering.

3. People-Clustering May Interfere with Plug-Load Management

For people-clustering to be most effective, plug loads must be managed as well; however, the most sophisticated plug load management tools, which are internet-based and rely on algorithms, depend on the predictability of electricity demand at outlets to determine when and where to turn off plug loads at those outlets. People-clustering makes space utilization and electricity demand at outlets less predictable, so it remains to be seen whether people-clustering will be able to accommodate the more sophisticated versions of plug load management. 

4. No Guarantee of Base Building Energy Savings

To be a “home run” as a strategy for aligning energy use with occupancy, people-clustering would have to produce significant energy savings for the base building components of HVAC systems in real time, which is an outcome that is far from certain. It is good to turn down or turn off VAV boxes in unoccupied HVAC zones, but VAV boxes do not use that much energy. To achieve the most significant whole-building energy savings, the goal must be to maximize energy savings upstream, but as a practical matter instantaneous communication from the VAV boxes to the air handlers to the building management system to the chillers often breaks down and building staff must be available to manually change settings such as chilled water temperatures. 

Strategy #3: The Three- or Four-Day In-Office Workweek

A third solution for aligning energy use with fluctuating occupancy is the three- or four-day in-office workweek. To accommodate its employees’ desires for remote working, an employer would simply designate three or four days each week as in-office workdays for all its employees and designate the other one or two days as remote working days for all its employees. On the remote working day(s), the office would be closed.

This solution is simple because it does not require people-counting devices that are integrated with HVAC system controls (like the people-counting strategy) or daily sorting of HVAC zones into occupied and unoccupied spaces (like the people-clustering strategy). Instead, on the day(s) of the week employees are working remotely, the base-building HVAC set points would be changed to “unoccupied” status, which would reduce HVAC service to match the nonexistent or very limited weekend and holiday HVAC service that has been a familiar part of commercial office building management practice for decades. Similar to standard weekend and holiday building operations, additional energy savings would accrue on the remote day(s) from turning off all lighting, forgoing office cleaning and (if an entire elevator bank is on the same schedule) leaving only one elevator running.

The three- or four-day in-office workweek is highly effective at reducing whole-building energy use – something the people-counting or people-clustering approach may not accomplish – by turning down the base-building components of the HVAC system where most of the energy is consumed. 


While two of the three strategies presented by engineers, people-counting and people-clustering, present opportunities, they also face significant barriers as solutions for aligning energy use with occupancy in the hybrid workplace. The three- or four-day in-office workweek is virtually guaranteed to produce significant whole-building energy savings, but it may not be compatible with every company’s business model. In addition to these energy alignment strategies, engineers offered several other ideas for post-pandemic whole-building energy savings that are not focused exclusively on the hybrid workplace. Part 4 of this series will dive into these solutions for energy savings regardless of the occupancy profile. 

Other Posts in this Series

The rest of this series will answer two key questions: 

What were the causes of the Great Disconnect and what lessons can be learned from it that can help drive greater energy efficiency in commercial office buildings after the pandemic ends?
If hybrid workplaces become prevalent after the pandemic, what are the best strategies for matching office building energy consumption with the number of occupants actually in their offices?

Part 1:  Introduces the “Great Disconnect” and describes the importance of the phenomenon.

Part 2: Dives into the causes of the Great Disconnect

Part 4: Focuses on feasible and cost-effective solutions for aligning energy use with occupancy regardless of the occupancy profile. 


This series, co-written by Stephanie Margolis of the NYC Climate Action Alliance and Marc Rauch of the Environmental Defense Fund, is adapted from Marc’s report titled “Aligning Energy Use with Occupancy in New York City Office Buildings: Lessons Learned from the ‘Great Disconnect’ and Strategies for the New Hybrid Workplace.” Data supporting all claims was drawn from a literature review on pandemic and post-pandemic office energy use, more than two dozen interviews with building owners, tenants, data analytics providers, engineers, architects, and other professionals conducted by Marc, then Senior Specialist, Energy Transition Strategy at EDF, between October 2020 and May 2021, and energy-use data provided by building owners, large tenants, and third-party providers. We would like to acknowledge that the term ‘The Great Energy Disconnect’ was first used by Urban Green Council at an event of the same name on December 8, 2020.