System: Variable Air Volume

Assessment Tools

Technical Barriers to Decarbonization

Insights from Empire Building Challenge

Large commercial and residential buildings must overcome various hurdles before implementing deep retrofits or capital projects that help achieve building decarbonization. This section addresses technical barriers and questions often faced by building owners and retrofit project developers.

Decentralized Systems and Tenant Equipment

  • Access to Occupied Spaces.
  • Lease Concerns.
  • Regulatory Limitations of Rent Stabilized Apartments.
    • The building owner is required to provide free heat and hot water.
    • No mechanism to recover investment in new systems is necessary to achieve decarbonization.
    • Buildings are capital constrained.
  • Split Incentives (e.g. tenants pay for energy).

Facade and Windows

  • Work must be completed at the end of facade/window useful life; very long useful life.
  • Building codes.
  • Glazing reduction at odds with aesthetic/marketability concerns.
  • Difficult installing with occupied spaces.
  • Reduce Local Law 11 recurring cost via overcladding
    • Aesthetic concerns
    • At odds with historic preservation
    • Capital intensive
    • Lot line limitations
  • Technology Limitations
    • Need higher R-value/inch for thinner wall assembly:
      • Vacuum insulated panels
      • Aerogel panels/batts
      • Zero-GWP blowing agents for closed cell spray foam (nitrogen blowing agent needs to be more widely adopted)

Ventilation

  • Energy Recovery Ventilation (ERV)
    • Space constraints
    • System tie-in point accessibility/feasibility
  • Rooftop Supply Air (Reznor) Unit Alternatives
    • Heat pump alternatives to eliminate resistance heat
    • Combine with ERV
  • HVAC Load Reduction (HLR) Technology
    • Vent or capture exhaust gases
    • Space constraints
    • System tie-in point accessibility/feasibility
  • Central vs. Decentralized Ventilation Systems
  • Direct Outside Air System (DOAS)
    • Modular perimeter ducted air heat pumps:
      • Competition for leasable space
      • Space constraints
  • Ventilation Points-of-Entry
    • Aesthetic concerns
    • Lot line facades/building setbacks
    • Competition with leasable space
    • Space constraints

Heat Pump Limitations

  • Variable Refrigerant Flow (VRF)
    • Fire and life safety concerns about volume of refrigerant gas located within occupied spaces.
  • Regulatory risk from new refrigerant policies
  • PTAC and VTAC
  • Ducted Supply/Exhaust Air Source Heat Pumps
  • Domestic Hot Water
    • Central DHW Systems:
      • Limited domestic production.
      • Performance not confirmed by independent third parties.
      • More demonstration projects needed.
    • Decentralized DHW Systems
  • More open-source interconnection between devices/interoperability is needed to achieve energy distribution flexibility and capacity expansion:
    • Air source that has a manifold connection to interconnect with water source or refrigerant gas distribution.
    • Interconnectivity/simplified heat exchange between refrigerants/water/air, etc.
    • Other options and add-ons.

Steam Alternatives and Barriers

Below are high temperature renewable resource alternatives to district steam. These alternatives are limited and face barriers to implementation due to cost, scalability, and other factors. 

  • Deep Bore Geothermal
  • Renewable Hydrogen
  • Carbon Capture and Sequestration
  • Biomethane
  • Electric Boilers
  • High-temperature thermal storage
  • Hight-temperature industrial heat pumps
  • Waste Heat Capture and Reuse
  • Fission

Barriers to Electrification and Utility Capacity Limitations

Building Electric Capacity Upgrades

  • Electric riser capacity
  • Switchgear expansion
  • New service/vault expansion/point-of-entry space constraints
  • Capacity competition with other electrification needs:
    • Space heat and cooling
    • DHW
    • Cooking
    • Pumps and motors

Local Network Electric Capacity Upgrades

  • Excess Distribution Facility Charges (EDF)
  • Contributions in Aid of Construction (CIAC)

Gas Utility Earnings Adjustment Mechanisms (EAM) focused on System Peak Demand Reductions

  • Partial Electrification concepts achieve deep decarbonization but do not necessarily achieve peak gas demand reductions (debatable)

Total Connected Loads and Peak Demand drive need for capacity upgrades

  • Demand reduction strategies do not obviate capacity limitations unless the utility accepts the solution as a permanent demand/load reduction strategy.
    • Battery Storage:
      1. Fire danger
      2. Space constraints
      3. Electricity distribution limitations
      4. Structural loads
    • Building Automation/BMS/Demand Response:
      1. Cost
      2. Integration limitations; Blackbox software
      3. Microgrid development cost and lack of expertise
    • On-site Generation:
      1. Space constraints
      2. Gas use; Zero carbon fuels availability is non-existent
      3. Structural loads
      4. Pipe infrastructure

Thermal Storage

  • Space constrains
  • Structural loads
  • Technology limitations:
    • Vacuum insulated storage tanks
    • Phase change material (DHW, space heating)

Geothermal (ambient temperature), Deep Bore Geothermal (high temperature) or Shared Loop District Energy Systems provide cooling and heating with lower peak demand than standard electric equipment

  • Building pipe riser limitations; need additional riser capacity:
    • Building water loops are typically “top down” – cooling capacity is typically located at rooftop mechanical penthouses; cooling towers at roof. Some exceptions to this rule
    • Space Constraints
  • Drilling Difficulty:
    • Outdoor space constraints for geothermal wells
    • Difficult permitting
    • Mud and contaminated soil disposal
    • Overhead clearance constraints for drilling in basements/garages 
  • Shared Loop/Thermal Utility Limitations:
    • Requires entity that may operate in public ROWs and across property lines
    • Utilities are limited by regulations for gas, steam or electric delivery versus shared loop media (ambient temperature water).
      1. Only utility entities can provide very long amortization periods
      2. Utilities are best suited to work amid crowded underground municipal ROWs.
  • Deep Bore Geothermal Limitations:
    • Requires test drilling and geological assessment
    • Seismic risk
    • Drilling equipment is very large – more akin to oil and gas development equipment
    • Subsurface land rights and DEC restrictions

Other Energy Efficiency/Conservation Measures with proven/attractive economics (these measures are limited by lack of capital or knowledge)

  • Lighting with lighting controls
  • High-efficiency electrically commutated motors (ECM)
  • Variable Frequency Drives (VFD) on pumps and motors
  • Retro-commissioning tasks and maintenance

Behavioral Modification

  • Staggered work scheduling
  • Telework

Submetering and billing, potentially creates split incentive between landlord and tenant

Crossover Device or “Magic Box” Technology

These include multi-purpose technology for heating, cooling, heat exchange and ventilation, filtration, and/or domestic hot water.

  • Domestic production and supply chain is limited.
  • Small players operating in this space.
  • Technology is not tested over long operational periods (providers include: Daikin, Nilan, Zehnder, Drexel und Weiss, Minotair, Build Equinox, Clivet).

Zero Carbon Fuel Limitations

  • Green Hydrogen
  • Renewable Natural Gas

Low-Carbon Fuels

  • Biofuel
  • Biomethane

Renewable Energy Procurement Limitations

  • REC Purchasing:
    • NYSERDA monopolizes REC purchasing from renewable energy projects.

Pending Carbon Trading Programs Limitations

  • Deployment timeline is highly uncertain.
  • Price per ton of carbon is highly uncertain and will likely be volatile/low based on previous emissions trading scheme outcomes.

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Engineering Solutions

Low Carbon Multifamily Retrofit Playbooks

These playbooks summarize retrofit strategies that maximize occupant comfort and energy savings through a transition from fuel to electricity- based heating, cooling and hot water systems.

Playbooks are organized by building system— lighting & loads, envelope, ventilation, heating & cooling, and domestic hot water– detailing common existing systems, typical issues, and recommended measures.

View Report(opens in new window)
Source: Building Energy Exchange

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Strategic Decarb 101

Seven Misconceptions About Decarbonization

Insights from Empire Building Challenge

It is clear today that the use of fossil fuel-fired equipment in buildings has a limited future due to technological advancements, policy changes, ESG requirements, and other externalities. As asset managers, sustainability managers, and their consultants pursue decarbonization plans, misconceptions about decarbonization arise that can delay action and progress. Below is a list of the misconceptions encountered by NYSERDA’s Empire Building Challenge team and our recommended approaches that debunk these inaccuracies. 

1.
Simple Payback Measures

Instead of looking for tangential ways to create value, energy efficiency and decarbonization projects repeatedly fall into the trap of using energy savings (and some may now include carbon emissions fines savings) to justify investments in energy conservation measures. Often, this linear thinking approach yields unattractive investment economics. Alternatively, conduct scenarios analyses including net present value calculations: The lowest net present cost or negative net present value (NPV) over the decarbonization period will help inform the prioritization and selection of energy conservation measures. Demonstrating the return on investment (ROI) and/or internal rate of return (IRR) on the incremental cost of action over a do-nothing baseline will help persuade real estate owners to prioritize these projects. Rather than a simple payback analysis that looks only at the decarbonization path, the analysis should focus on comparing a decarbonization path with a “business-as-usual” path. This approach helps isolate the incremental cost of decarbonization over a business-as-usual approach. 

This type of analysis requires completing a Strategic Decarbonization Assessment (SDA), which is based on a Discounted Cash Flow (DCF) analysis over the decarbonization period. The SDA should include the complexities of a capital refresh, tenant improvements, and non-energy benefits. Asset investment should be in the context of a comprehensive decarbonization roadmap rather than simply reactive maintenance.

2.
One-to-one Equipment Swap with Air Source Heat Pump Is the Best Electrification Option

A one-to-one equipment swap with air source heat pumps, which is typically the first full-electrification option considered, may not be a realistic decarbonization strategy – particularly for owners of large buildings facing various constraints around thermal distribution systems, roof space, tenant disruption, and energy supply. In fact, it is advantageous to determine the building’s need for heat pumps toward the end of the decarbonization road mapping process to ensure that the heat pumps can run optimally. Significantly reducing loads, recovering and reusing heat wherever possible by enabling thermal networking, and using a cascading approach to decarbonizing easy-to-electrify loads are likely advantageous steps to take before installing heat pumps. Systems should be optimized to deliver heating or cooling efficiently over the integrated sum of the year’s diverse conditions, the vast majority of which are at part-load. Efforts to reduce and shift loads can help reduce peak capacity. However, electrification of more difficult peaks may require special consideration within the building’s roadmap and taking a rational approach to resilience and accounting for evolving electric grid or thermal network supply conditions. This is the foundation of Resource Efficient Decarbonization.

3.
Electrify Everything… Immediately and All at Once!

Perhaps because the electrification movement was born in mild-climate California, the cold-climate, tall-building narrative has been incomplete. Decarbonization skeptics suggest that if it doesn’t make sense to electrify everything in one simple move, then it doesn’t make sense to electrify anything.  The reality is that tall buildings in cold climates like New York must overcome space constraints and distribution challenges to provide comfort at peak load conditions without straining the electric grid or requiring oversized, sticker-shock-inducing equipment capacity.

A more suitable slogan for Northeast electrification champions would be “Electrify Everything Efficiently.” Engineers should model building energy consumption data across granular temperature bins (see Figure below) and plan for electrification with “easy” loads like domestic hot water, then mild temperature loads (typically representing 80%+ of total loads), and finally for the extremes. This is the cascade approach. Until a viable solution emerges, a building owner might even keep a small gas-fired boiler and their steam radiators around as a reserve as they learn to grapple with resilient functionality at heating design conditions. Despite global average temperatures increasing, cold snaps may even become more extreme due to a collapsing winter Polar Vortex.

Annual Energy Usage by Temperature Bin

4.
Technology Installed Today Will Be Obsolete Tomorrow

There are plenty of technology-neutral enabling steps to take prior to committing to a particular low-carbon retrofit technology. Buildings are constantly evolving and exist on a continuum unless demolition is planned. Reducing loads, enabling thermal recovery, sharing and networking, and implementing grid interactivity are all priority measures that might take place prior to electrifying heat sources. Consultants also must determine the value of inaction and the value at risk if a building owner decides to do nothing. Balancing this risk with the pace of technological innovation is a delicate analysis and is impossible to conduct without a Strategic Decarbonization Assessment. When in doubt, look to leverage existing infrastructure like using chilled water loops for heating to replace partial loads. Electrifying perimeter heating used during extreme temperatures may be a later priority or absent from the critical path on a strategic decarbonization roadmap. Look to the case studies emerging out of the Empire Building Challenge for more information on this strategy.

5.
My Tenants Don’t Think This is a Priority

Consider the tangential benefits of pursuing decarbonization early. For example, more and more Class A tenants are demanding environmental action from landlords to comply with shareholder environmental, social, and corporate governance (ESG) requirements. Accelerating facade improvements may reduce the need for invasive and expensive maintenance down the line. Indoor air quality, improved comfort, and operability are emerging priorities among all tenant types. 

6.
Electricity Produces Emissions

Yes, but not for too much longer. States are legislating 100% carbon-free electric grids like New York did in the Climate Leadership and Community Protection Act (Climate Act). Modeling total emissions over time using declining electric grid carbon emissions coefficients across multiple decarbonization scenarios is an important task. Phasing in electrification over time and in a strategic way is the only pathway to eliminating on-site emissions.

Chart, line chart Description automatically generated

7.
It’s Too Disruptive and Expensive to Decarbonize a Building All at Once

Achieving carbon neutrality typically requires and benefits from a phased approach versus decarbonizing all at once. Incremental implementation of low-carbon retrofits across a continuum is critical to reaching building operations carbon neutrality in cold climates. Evaluate the cost-effectiveness of phasing and maintaining technology optionality and the risk mitigation benefits these efforts might deliver. Decarbonization efforts fall on a decision-making tree, which evolves as time elapses and technology, policy, or other conditions change; each branch of the decision-making tree is a new decision point. Sustainability and asset managers can plan these intervention points over the decarbonization period.

Chart, diagram Description automatically generated with medium confidence

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Engineering Solutions

Empire Technology Prize

The Empire Technology Prize is a $10 million competitive opportunity for global solution providers focused on advancing building technologies for low-carbon heating system retrofits in tall commercial and multifamily buildings across New York State. This NYSERDA initiative, administered by The Clean Fight with technical support from Rocky Mountain Institute, includes a $3 million sponsorship from Wells Fargo. Accelerating low-carbon building retrofits is fundamental to New York State’s national-leading Climate Act agenda, including the goal to achieve an 85% reduction in greenhouse gas emissions by 2050.

Learn about Empire Technology Prize.(opens in new window)
Source: via The Clean Fight

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Assessment Tools

Intervention Points and Best Practices

Insights from Empire Building Challenge

Prioritizing Decarbonization Interventions 

While each individual building has a unique capital improvement plan and timeline, retrofit projects or decarbonization interventions may be organized and grouped by similarity as property owners plan for the future. Below is the overarching hierarchy for decarbonization intervention points according to industry best practices:

  1. Facade Upgrades
  2. Windows Upgrades
  3. Ventilation Upgrades with Energy Recovery Ventilators (ERV)
  4. Maximize the reduction of distribution temperatures
  5. Maximize surface area of terminal units
  6. Supplement 90% of peak load with hybrid electrification strategies
  7. Eliminate peak load “last-mile” with innovative strategies in storage and/or thermal demand response
  • Delay replacement of gas-fired equipment with new gas-fired equipment as long as possible. Rebuild and maintain existing equipment until replacement.
  • Replace all remaining non-LED lighting and include lighting controls at the time of retrofit
  • Seal rooftop bulkhead doors and windows.
  • Add smoke-activated fire dampers or annealed glass to the elevator shaft vent grill in the elevator machine room.
  • Install algorithmic controls on top of the existing boiler control system.
  • Balance steam distribution systems:
    • Identify condensate return leaks.
    • Right-size air vents and master vents.
    • Ensure all radiators are properly draining condensate.
    • Ensure all steam traps are functioning properly.
  • Implement Radiator Efficiency and Controls Measures:
    • Install thermostatic radiator valves (TRV) where possible.
    • Install RadiatorLabs radiator cover systems where possible (integrate with algorithmic boiler control).
  • Balance air supply and ventilation systems using proper air registers, louvers, dampers, and technology like Constant Airflow Regulator (CAR) dampers:
    • Need innovative methods of balancing temperature across commercial office floors (heat shifting and sharing from one building exposure to another, e.g. north vs. south).
    • Balance air supply and return across vertical pressure gradients.
    • Seal vent stack perforations/leaks (e.g. mastic sealer).
  • Increase efficiency of pumps and motors:
    • Add VFD controllers to all pumps and motors.
    • Replace rooftop exhaust fans (e.g. mushroom fans or similar) with electronic commutated motors.
  • Implement algorithmic controls on top of existing Building Management Systems (BMS) in commercial office buildings.
  • Hybrid Domestic Hot Water (DHW) Plants: Add DHW heat pump equipment to an existing gas fired DHW plant.
    • Consider the option to direct bathroom exhaust air to DHW heat pump equipment.
  • Install Energy Recovery Ventilation (ERV) system.
  • Install rooftop solar.
  • Procure New York State-sourced renewable power.
  • Procure biomethane from utility via pilot program.
  • Procure renewable hydrogen blend from utility via pilot program.
  • Develop innovative means of participating in gas demand response:
    • Delay boiler firing with controls or other means.
    • Procure biodiesel blend for fuel switching requirement.
    • Thermal storage and hybrid plants (electrification)
      • DHW electrification (partial or full load)
      • Split system or PTAC partial load heating electrification
  • Add central-control compatible thermostats to apartments and office suites to control decentralized heating and cooling systems.
    • Enable aggregate demand response activity.
  • Fully electrify DHW systems:
    • Air source DHW heat pump.
    • Resistance DHW.
    • High-efficiency thermal storage.
    • Supplement with solar thermal where compatible.
  • Overlaid or insulated masonry facades with high ongoing Local Law 11 cost.
  • Eliminate uninsulated radiator cabinets/niches in exterior walls.
    • Install wall-mounted slim radiators with TRV or other controls.
    • Install RadiatorLabs technology.
  • Begin routine window replacement plan with high-performance windows.
  • Support cogeneration systems with biomethane (injection) procurement.
  • Explore hydrogen (injection) procurement to support cogeneration and centralized heating plants.
  • Develop on-site battery storage systems to manage building load profiles and reduce peak usage.
    • Integrate with an existing on-site generation where compatible.
  • Increase thermal mass/thermal inertia and expand thermal storage capacity using Phase Change Material (PCM) products. Products currently include: ceiling tiles, wall panels, AHU inserts, thermal storage tank inserts:
    • Embrace overnight free cooling.
    • Shift loads associated with thermal demand.
    • Capture and store waste heat.
  • Implement centralized or in-building distributed thermal storage systems to shift thermal loads to off-peak periods.
  • Convert low-temperature heating distribution systems to shared loop systems or geothermal systems; building distribution is already optimized for low-temperature distribution: water source heat pumps, large surface area terminal units (radiant panels, underfloor heat, fan coils, etc.)
    • Interconnect with early shared loop system phases (private or utility-led).
    • Eliminate cooling tower as a primary cooling system (may remain as a backup as feasible).
  • Where necessary, convert high-temperature heating distribution systems to low-temperature distribution systems; systems converted from fin tube to radiant panels, fan coils, or water source heat pumps as feasible.
    • The supplement heat source for hydronic heat pumps with solar thermal technology (water source heat pumps).
  • Embrace consumer products that reduce building loads and peak demand:
    • Appliances with onboard battery storage.
    • Networked smart appliances.
    • Power over Ethernet (PoE) DC-powered, low voltage products.
      • DC power distribution networks make use of on-site renewable energy and energy storage.
  • Advanced DC[1] and AC/DC hybrid Power Distribution Systems[2]
  • Install HVAC Load Reduction Technology:
    • Capture VOCs and CO2 in liquid sorbent.
    • Engage with the liquid sorbent management company to safely dispose of scrubbed gases (carbon sequestration, etc.).
    • Use buildings hosts for negative carbon technology and focusing on direct air capture to achieve larger decarbonization goals (carbon capture and sequestration)
  • Electric Distribution Upgrade Needed:
    • Begin replacement of centralized heating systems with decentralized heating and cooling systems where appropriate. Technology includes: PTAC, VTAC, ducted PTAC, VRF, and similar technology.
    • Replace stoves, ranges, and cooktops with electric equipment: resistance, convection, or induction.
    • Integrate Building Distribution with an advanced electric vehicle (EV) charging network to provide power to parked EVs and to extract power at peak periods (EV owners opt-in for reduced parking rates, other benefits, etc.).
  • Install multi-function glass during window or facade replacement:
    • Install building-integrated PV during facade retrofits.
    • PV glass.
    • Electrochromic glass.
    • Vacuum Insulated glass.
  • Install highly insulated panels at spandrels:
    • Vacuum insulated panels.
    • Aerogel insulated panels.
  • Replace cooling towers with advanced heat rejection technology:
    • Passive radiative cooling technology.
  • Interconnect with 100% hydrogen distribution network.
  • Pair advanced, on-site battery storage systems with hydrogen fuel cells.

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Strategic Decarb 101

Advanced Building Construction Collaborative Case Studies

These case studies cover projects that will dramatically reduce carbon emissions with deep energy retrofits for affordable multifamily housing in the Boston area. Deep energy retrofits dramatically reduce carbon emissions. These renovations transform affordable housing to be highly energy efficient, all-electric, powered by clean renewable energy, and renovated with materials low in embodied carbon. These projects are part of the Advanced Building Construction Collaborative’s demand aggregation. This work aims to demonstrate streamlined deep energy retrofits and retrofits using advanced building construction techniques to accelerate the adoption of this work in the market.

View Case Studies(opens in new window)
Source: Advanced Building Construction Collaborative

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