Building Science & Decarbonization Primer

A backgrounder by Marc for people coming from outside the building science/ energy efficiency field.

“We shape our buildings and they shape us” -Churchill

Why Building Science

Identifying the upgrades that make the most sense for a particular building requires understanding building science.

From Wiki: “Building science traditionally includes the study of indoor environment and building resource use including energy and building material use. These areas are studied in terms of physical principles, relationship to building occupant health, comfort, and productivity, and how they can be controlled by the building envelope and electrical and mechanical systems. The practical purpose of building science is to provide predictive capability to optimize the building performance and sustainability of new and existing buildings, understand or prevent building failures, and guide the design of new techniques and technologies.”

Here is a Joe Lstiburek video that gives a flavor of how a passionate and articulate practitioner applies building science to walls and roofs. Lstiburek is pronounced “Stee-brek”)

With building science there is also a real human dimension to how the science plays out. Buildings are built by contractors that need to make things work in the chaos of a job site, maintained by operators who move from one (hopefully, figurative) fire to another and occupied by tenants that can subvert the best intentions of any design.

With so many failure points, simplicity is particularly important and – I would argue – implicit to the effective application of building science. If you are into tech… perhaps you are used to a “new for the sake of new” mindset. With a lot of real estate and construction, the mindset is often… “old for the sake of old.” When it comes to buildings, there is wisdom in any solution that has stood the test of time. As such, any disruptions to the status quo need to be grounded in a robust understanding of building science.

For a living glossary of terms relevant to this discussion, see the Building Science Glossary.

How Building Operations Impacts Climate - General

Buildings typically use electricity to power lighting, air conditioners, appliances, anything you plug into a wall, fans and pumps. Electricity is generated by a mix of sources including fossil fuel power plants, nuclear reactors and hydroelectric dams, wind turbines and solar panels. The portion of electricity generation that comes from fossil fuel power plants has a carbon footprint.

Most buildings also use fossil fuel (natural gas, oil or propane) on-site. This fuel is burned by equipment that provides useful heat for keeping people warm, heating up hot water for use at faucets (“domestic or service hot water”) and for appliances such as stoves and dryers. The onsite combustion of fossil fuel for all of these “end uses” has a carbon footprint.

As the electricity grid incorporates a higher and higher fraction of renewable energy, the carbon impact of electricity diminishes and on site fossil fuel combustion becomes even more significant.

How a building is used by people drives the system requirements for electricity and fuel using systems. In larger buildings, the 4 primary space use types are: multifamily residential, office, hotels and schools (in this order for NYC in terms of relative sector size – but in other orders in other cities). In NYC there are approximately ~1M buildings. Buildings over 50,000 SF represent only 2% of the total number of NYC buildings but ~50% of overall square footage. As such, building decarbonization policies in NYC and other cities have focused on addressing the impact of larger buildings above a threshold size cut-off at 25,000 or 50,000 square feet. The most common minimum regulatory requirement for these buildings is the annual public reporting of energy use through the EPA Portfolio Manager website. It is therefore these larger buildings where there is the most public data available.

Generally speaking, buildings where people sleep (multifamily, hotels & also dorms, etc) use more fuel per square foot than other kinds of buildings for two primary reasons: (1) in buildings where people sleep, spaces must be kept relatively warm every hour of every day in the winter (systems can’t be turned off nights and weekends); (2) the demand for domestic hot water is much more significant in such buildings.

Generally speaking, offices and schools use more electricity per square foot than buildings where people sleep as a result of the greater occupancy density and associated equipment for lighting, computers, ventilation, etc.

Building Operations and On Site Fossil Fuel Combustion

When it comes to on site fossil fuel, space heating is the biggest deal in terms of carbon. In a typical NYC multifamily building ~60% of overall carbon footprint is due to space heating. How much fuel a building uses for space heating is driven by both the efficiency of the heating equipment that supplies and distributes heat to the building and the performance of the building envelope & ventilation systems that dictate how much heat the building requires to keep people comfortable.

On the space heating supply side, boilers and furnaces burn fossil fuel and convert the energy from this input into steam, hot water or hot air that is used to distribute heat throughout a building. In the vast majority of NYC buildings, the burning of fossil fuel happens in a central mechanical room and the resulting heat is then distributed throughout the building. In this process, some useful heat is lost up the chimney. The “combustion efficiency” of a piece of heating equipment represents the fraction of energy from combustion that makes it to the building (rather than going up the chimney). Typical combustion efficiency is ~80% (i.e. ~20% of heat lost up the chimney) and varies only a few percentage points across most systems. Since combustion efficiency can be precisely measured, codes and standards focus on this parameter. Useful heat is also wasted when the building as a whole needs to be over heated because the right amount of heat is not distributed to the right individual spaces at the right times. The bigger the building, the harder it becomes to evenly distribute heat. In buildings over 25,000 SF, distribution efficiency is way more important than combustion efficiency and can vary widely from building to building particularly when it comes to the classic NYC steam heating system that drives residents to open windows throughout the winter. Distribution efficiency is however impossible to precisely measure and therefore is ignored by codes and standards. There are meaningful interventions to improve steam heating distribution efficiency described below.

On the space heating demand side, building lose energy in the winter to the outdoors via (1) heat conduction through walls, windows and roofs; (2) controlled movement of heated (“conditioned”) air out of a building via ventilation fans which is replaced by cold outdoor (“unconditioned”) air and (3) uncontrolled movement of heated air out of a building driven by natural pressure differences via gaps, cracks and open windows. Because conduction can be precisely measured, codes and standards focus on regulating the insulating properties of building materials to reduce its effects. Codes and standards also have a bunch to say about ventilation, although most older buildings built before modern (post war) codes don’t have any ventilation systems. And most buildings in NYC and other Northeast cities were built before such codes. Uncontrolled air movement is as big or a bigger deal as conduction or ventilation in most buildings. Uncontrolled air movement is however impossible to precisely measure and so gets less attention in codes and standards. There are gnarly interactions between archaic steam heating distribution system that can’t evenly supply heat throughout big buildings and uncontrolled air movement from open windows in over heated parts of those buildings.

When it comes to on site fossil fuel in buildings where people sleep, domestic hot water is the second biggest deal in terms of carbon. In a typical NYC multifamily building, ~20% of overall carbon footprint is due to domestic hot water. In these buildings boilers or hot water makers burn fossil to make hot water for sinks, showerheads and washing machines. Often the same heating boiler used for space heating is also used for producing domestic hot water. As with space heating, combustion efficiency applies and some portion of the fossil fuel used to create domestic hot water is lost up chimneys. In buildings over 25,000 SF the domestic hot water is continuously re-circulated throughout the building so that occupants don’t have to wait too long for hot water to start flowing from the tap. There is energy waste associated with this re-circulation but there are not pragmatic alternatives to reducing such distribution waste (would involve insulating pipes buried in walls or completely re-configuring buildings). “Low flow” showerheads and faucet aerators that provide sufficient (but not excessive) gallons per minute of flow can however be easily added to existing plumbing fixtures in order to somewhat reduce demand for hot water.

In buildings where people sleep, they also tend to want to cook. Cooking gas represents 1% of overall carbon footprint in such buildings. A gas stove is an open flame with combustion by products that are almost never directly expelled to the outside. There are significant health problems, particularly in children associated with unvented gas stoves. These problems are more severe in more densely occupied, affordable housing. Replacing gas stoves with electric stoves has minimal carbon impact but may represent the single most impactful building intervention to improve public health. See further reading for more information.

Where is the Fuel Burned?

Robin has pulled data for commercial and multifamily buildings over 10,000 SF from the Department of Energy to come up with some neat heat maps illustrating how much fossil fuel is burned, where across the country.

Where Our Fuel is Burned in Buildings Above 10,000 SF

Spoiler alert: with the notable exceptions of highly populous CA, FL & TX, most of our fuel is burned in regions where climate is colder and the building stock is older in the Northeast, Mid-Atlantic and Upper Mid-west.

Some heartening take-aways for C1.5 (1) NY is a great place to start (2) Any lessons learned and solutions proven in NY will be highly relevant to the important adjacent markets with similar building intervention opportunities (3) An impactful national strategy need not require traction in 50 states – focusing on a dozen states (most of which have progressive policy tail winds) will get us almost all the way there.

We can do this!

Spotlight on the Multifamily Segment

Putting it all together, C1.5 is initially focused on applying building, data and behavioral science to the largest segment (multifamily) in the largest city in North America (NYC). Within this segment, the reduction and ultimate elimination of fossil fuel energy use is most significant part of the problem. Approximately 80 percent of the carbon footprint in these buildings is driven by fossil fuel for space heating and domestic hot water – a share that will only increase as the carbon footprint of the remaining ~20% decreases with a cleaner electric grid.

What we learn from streamlining decarbonization in multifamily buildings in NYC will ultimately be translatable to other sectors and other cities. If we can make it in NYC, we can hopefully make it anywhere… starting with the Northeast, Mid-Atlantic and Upper Midwest geographies where the climate is colder and the building stock is older.

It is also relevant to understand that the multifamily sector has been historically overlooked, especially by larger national organizations. While these buildings make up a large fraction of the built environment in major metro areas, single family homes and commercial buildings make up a much higher fraction of our stock outside of cities. Since more recent building decarbonization market growth is being driven in large part by municipal policies and regulations, the multifamily sector is getting increasing attention and Bomee, Marc (and SWA’s) 20 years of experience in this segment is core to C1.5’s differentiation.

Beyond (1) C1.5 business strategy; (2) the sheer size of this segment in NYC; and (3) the significance of its fossil fuel carbon footprint in any city, multifamily buildings house a disproportionate share of lower income residents. Historic under-investment in housing quality therefore results in unique opportunities to coordinate decarbonization upgrades with other work that tangibly improves quality of life. Moreover, progressive legislation that is driving climate action tends to stipulate that ~40% of the benefits of clean energy investments are directed to disadvantaged communities, further underscoring the centrality of the multifamily segment.

Metrics & Frameworks

Energy efficiency refers to getting more output for a given amount of energy input. Example: a LED light bulb that provides more light for a given amount.

Energy conservation refers to reducing the demand for outputs that require energy to produce.

Example: turning off that LED light bulb when no one is in the room.

These terms have been used widely since Jimmy_Carter_in a_fireside_chat asked people to put on sweaters and turn down their thermostats and manufacturers to build more fuel efficient cars 50 years ago!.

In order to state off the worst potential impacts of global warming, the Intergovernmental Panel on Climate Change (IPCC) says that the world must be carbon neutral by 2050 and achieve a 50% reduction in carbon emissions (from a 2010 baseline) by 2030. The required changes to our infrastructure required by 2030 represent a 10x change from business as usual. The 2020’s are considered the decisive decade.

While Efficiency and Conservation are critical to meeting such targets, we cannot “Efficiency” or “Conserve” our buildings (or cars) all the way to zero carbon. Deeper goals have required a paradigm shift and highlighted the importance of converting existing fossil fuel based equipment to electricity driven equipment that can be connected to a clean grid. Such “electrification” generally requires much more significant changes to building infrastructure than basic efficiency and conservation.

Building decarbonization involves the combination of efficiency, conservation and electrification in buildings with the supply of renewable electricity in order to reduce carbon footprint to zero.

How much energy buildings use will always impact operating costs. And unnecessary waste is of course stupid. But a decarbonization framework is much more about abundance (use as much energy as you want to pay for as long as it is clean) rather than scarcity. There is therefore some promise that this concept may be more “marketable” to people in certain developed countries that don’t want to do without anything (whether addressing climate justice “ought” to need to be marketable is another conversation). It is also important to be clear eyed that most entrenched industries do not want to fundamentally reinvent societal infrastructure, fast enough. While it is not going to be easy and at least we have the metrics to know where we stand and to measure our progress.

Systems Thinking to Mitigate Impacts

In an industry divided into various trades and design specialties, Building Scientists have drawn attention to the need for “Systems Thinking” in order to drive deeper optimization. Examples of systems thinking include

1. Understanding how all the parts of steam heating system from the boiler in the basement to the piping throughout the building must work in concert in order to keep people comfort and minimize energy use. Clanging_Pipes_and_Open_Windows

2. Spending more money on a building enclosure that reduces building heating requirements and “downsizing” the heating system accordingly.

3. Paying attention to how building operations can cause “back_drafting” of combustion appliances.

A limitation of “The Building as a System” framework that has become apparent with deeper decarbonization goals is that even drawing the system boundary around the whole building is inadequate. Per above, we need to include the electric grid that supplies the building and optimize that overall network. For any building that burns on site fuel today, the pathway to carbon neutrality involves switching out fossil fuel equipment on site with heat pumps AND supplying buildings with carbon free electricity.

Some (Daunting) Historic Precedents

It is well documented that new building technology solutions face steep acceptance hurdles and going from brand new technologies to wide scale adoption tends to take decades.

According to Cool: How Air Conditioning Changed Everything, the percent of homes with A/C in at least one room was 4% in 1955 and 87% in 2014. Near complete market saturation of a proven (but expensive) technology took 60 years!

This data point is consistent with other_findings that it takes decades to go from “energy research” to practical application …and then perhaps another three to four decades before that technology is widely deployed throughout the global energy market, we will likely have to combat global warming with technologies that are already developed.”

As far as C1.5 is concerned, we are not waiting on some silver new piece of hardware bullet. Fortunately, all the basic building upgrade technologies that we will need to meet 2050 targets exist. Yes of course there will be incremental improvements in such hardware over the next couple of decades but the fundamental technology is all commercially available today. Our work is about accelerating the adoption of such proven solutions with software.

Existing Buildings versus New Buildings

Fundamentally, there are really only two kinds of buildings: the ones that exist today and the ones that haven’t been built yet. We need to of course do it all. New buildings are a lot easier and very close to being solved from a decarbonization standpoint. Existing buildings are much farther from being solved (a lot of white space). In already built out parts of the world (such as NYC), existing buildings are also the biggest piece of the pie. In NYC, 90% of buildings that exist in 2050 are already with us today.

An easy way to understand why existing buildings are so challenging is to compare them to new buildings. During a new construction process there is a development team focused on completing a major project, a bank that provides the necessary resources and a multi disciplinary design and construction team to execute. At no other time in it’s lifecycle will so much human and financial capital be brought to bear on that asset. In this case, getting to better outcomes involves incremental tweaks such as inserting some new technology into a process already in motion.

With existing buildings, there is not such a robust process to leverage. The mindset of existing building operations (as opposed to ground up new construction “developers”) also tends to be more about “keeping things running,” rather than “re-imagining.”

There are however some footholds available when it comes to climbing the existing building mountain. The risk mitigating, “if it ain’t broke don’t fix it” worldview of many real estate operators means that there is an opportunity to intervene at the end of useful life of major systems. At this point in time, when some money needs to be spent no matter what, a building retrofit is assessed relative to it’s incremental cost versus a business as usual “like for like” replacement. For instance, code minimum new windows may cost $1M and better performing alternative may cost $1.2M – at the time the building owner is ready to make some investment in windows, it is only the incremental $200k that needs to be justified.

And often just as importantly, whether you put in good or crappy windows involve about the same allocation of human capital in terms of installation labor, disturbance to tenants and landlord headaches. So the good news is that catching all building systems at these points makes up-selling better alternatives much easier. And if windows are typically replaced every 30 years that means that every year about 3% of buildings are doing windows. The bad news is that since most major building systems have a service life of about 20-30 years, between now and 2050 (when the IPCC says we need to be carbon neutral), we only have one shot to be in the right place at the right time. (i.e. windows replaced in 2025 won’t be replaced again till 2055).

Adding to this logistical challenge, most major building systems don’t of course all need to be replaced at the same time. Back to good news, useful life is a squishy concept… a boiler doesn’t go from being perfectly functional at 24 years and dysfunctional at year 25. And there are also certain times in the life of an asset when major capital dollars are reinvested such as when buildings are refinanced or sold. I will never forget when, thinking I was giving hard nosed business advice, I told an owner of one of the largest buildings in Manhattan that his heating system had some life left on it before he needed to sink a few million dollars. Since he had just refinanced the building, his response was, “yeah, but I have the money in my pocket now.” These times are perfect opportunities to guide capital dollars that were going to be spent anyway in the best possible direction and – while all that human capital is focused on the asset – line up other resources to drive an even more comprehensive scope.

It’s almost like someone should build a tool that sucks up all the public data and spits out the optimal way to retrofit whole cities of buildings over time and space.

Primary Types of Retrofits for Existing NYC Multifamily Buildings

Rather than view every building as a snowflake, such a tool would need to systematically define repeatable upgrades that map to different existing building conditions. Let’s call these repeatable types of upgrades “building blocks” in that they can be mixed and matched for a particular building in order to generate a more comprehensive upgrade scope (aka a retrofit scope “package”)

Under every heading below (i.e. Envelope Building Blocks vs. Lighting Building Blocks), the building blocks are numbered in order of least cost to greatest first cost. Besides cost, the primary other building considerations to decision making are (a) coordination of upgrades with “end of useful life” moments and (b) whether a particular upgrade requires work to be down only in (more readily accessible) common area spaces or if a substantial number of tenants need to open their doors for work to be done. In the case of the latter, upgrades that can be implemented over several years by in house operations staff, in coordination with other apartment entries can be advantageous (if there is an actual operations process established and maintained for this purpose…)

Envelope Building Blocks

1. Air sealing: sealing up the gaps, cracks and holes throughout a building to reduce uncontrolled air movement. Much of this work is a best practice for ongoing operations and maintenance.

2. Roof insulation: adding additional roof insulation to reduce heat transmission – usually near roof surface “end of useful life”

3. New windows: upgrading existing windows with new ones that lose less heat during the winter – always near window end of useful life

4. Increased level of wall insulation: in bigger buildings adding additional insulation is not very common since walls don’t typically have an end of useful life and (unlike in the case of 2x4 wood framed single family homes) with higher rise masonry construction, there tend not to be convenient cavities to “blow in” insulation. “Re-skinning” ugly (to most) post war buildings with exterior foam and stucco over existing brick to improve aesthetics, water management and insulation levels is worth evaluating. But no one is going to re-skin a beautiful pre-war building.

Note that in addition to impacting heating requirements, building envelope upgrades can improve occupant comfort. Drafts and interior surface cold spots associated with windows that transmit a lot of heat to the outside can make people uncomfortable. The (inferior) alternative to improving envelopes is to maintain spaces at warmer temperatures in order to compensate for poor envelopes.

Note also that building envelopes also impact cooling requirements. New windows can have glass with properties that allow visual light transmission but reduce “solar heat gain.” Roof surfaces get very hot (120 - 140 F) in the summer. Adding roof insulation along with white or silver paint on a flat roof surface to reflect solar heat gain can reduce cooling requirements in at least the top floor of a building. Keep in mind though that in a typical NYC multifamily building, energy use associated with cooling tends to represent ~5% or less of whole building carbon footprint.

Fossil Fuel Heating & DHW System Building Blocks

1. Existing heating equipment tune-up: making periodic adjustments to the moving parts of this equipment to improve the combustion efficiency by 1-2%.

2. In unit low flow fixtures: screwing in showerheads and faucet aerators at fixtures to adjust gallon per minute flow rates to lower but still adequate levels

3. Heating distribution tune-up: improving the ability of the heating systems to deliver the right amount of heat to the right spaces at the right times through add on valving & control upgrades throughout a building (particularly in apartments). Particularly relevant to steam heating systems. See Additional Resources at bottom for further details.

4. Heating equipment replacement: replacing existing boilers with more efficient equipment “right sized” to the heating requirements of a building & with improved combustion efficiency – always near boiler equipment end of life. Given that most equipment is already ~80% efficient and there are physical limitations to achieving much higher performance, combustion efficiency gains with newer equipment do not tend to be substantial (with some exceptions that apply to < 10% of buildings with particularly egregious existing conditions)

Lighting Building Blocks

1. In unit lighting: providing residents with screw in LED bulbs for their lamps or replacing hard wired fixtures with LED’s

2. Common area lighting: replacing corridor, stairwell, exterior and with LED and associated controls

Other Building Blocks

1. Appliances: replacing old refrigerators in apartments with ENERGY STAR models that use less electricity is the big one - always near refrigerator end of useful life.

2. Ventilation: upgrading exhaust ventilation systems serving bathrooms and kitchens so that they extract a balanced amount of stale air from apartments from the top to the bottom of the building. Usually has more of an indoor air quality benefit than a carbon impact. See Additional Resources for further details.

On Site Renewable Building Blocks

1. Solar Photovoltaic (PV): installing PV panels on building roofs to generate electricity. There has been a ton of innovation around PV on the business model side. The electricity generated can be used to offset on site electricity use. In this scenario, an owner can pay for PV panels with cash or enter into no money down financing arrangement with a third party with positive cashflow from Day 1. As an alternative to offsetting on site electricity use, third parties can broker deals to sell electricity to other people in a community (“Community Solar”) in a way that can be economically advantageous to the building owner.

2. Solar Thermal: installing panels on building roofs to generate hot water, that is used to offset domestic hot water produced by boilers. This alternative can be effective but involves much many more moving parts than PV and has seen much less business model innovation (in part because hot water is not as fungible as electrons)

Heat Pumps

1. Heat pumps for making DHW: installing electrically driven equipment that pulls heat out of even cold outdoor air to make hot water.

2. Heat pumps for space heating: installing electrically driven equipment that pulls heat out of even cold outdoor air to provide space heating without fossil fuel.

See More on Heat Pumps and Additional Resources for further details on heat pumps.

More on Heat Pumps

Heat pumps move heat “uphill” from cold to hot. This work pushing up hill takes electricity. A refrigerator that keeps food cold by pulling heat out of the inside compartment and rejecting that heat to the kitchen is a heat pump.

When it comes to building heating and domestic hot water, the most common types of heat pumps are “air source” heat pumps. Such heat pumps are able to pull heat out of even very cold outdoor air and move that heat into a building. An “air to air” heat pump moves heat from the outdoors to heat up air in a building for space heating An “air to water” heat pump moves heat from the outdoors to heat up water in a building for space heating or domestic hot water.

Heat pumps are a proven technology but have not been adopted widely in bigger buildings. We therefore still have a lot to learn about the practical building integration of this technology in bigger buildings.

In a typical NYC multifamily building, space heating electrification requires replacing infrastructure in every room of the building and is approximately 10x more expensive than DHW electrification which only requires upgrade work in boiler rooms.

As such, there is far greater potential for DHW heat pumps to be the application that gets to scale first… but we will ultimately need both

Given the importance of heat pumps to decarbonization goals, please take the time to check out this video/presentation_for_C1.5 for a bunch more details.

Deeper dive on NYC Retrofits

The above building block concept attempts to somewhat simplify the building decarbonization process.

There is plenty of jargon and other baggage that has been promulgated by the industry, primarily by the folks like energy utilities and their regulators that have been paying building owners to do efficiency and decarbonization retrofits for many years. Some people in the industry say it is more difficult to figure out how to negotiate such utility rebate programs than it is to actually implement upgrades in buildings!

This video ConEdison_ECM_Discussion_Video_for_C1.5 into the weeds on the specific building upgrade scope language used in NYS for multifamily buildings and the associated practical considerations with implementing such projects.

Given the centrality of Con Edison as our initial anchor customer, please take the time to watch this video (it is 90 minutes! – and our tech needs to distill this all down to 90 seconds)

While C1.5 aspires to not expose customers to such details in order to streamline decision making, having a basic feel for the underlying sausage making is important.

Utilities

As an aside, utilities are regulated monopolies that are increasingly being told by their state regulators to allocate larger sums of money to encourage building owners to invest in decarbonization upgrades. Utilities tend to listen to these regulators because they want to keep their position as the sole provider of electricity or gas in a territory.

There is a whole ‘nother handbook section that could be written on utilities. For now, in the context of C1.5:

1. Utilities are literally connected via wires to millions of customers. It is hard to imagine any building decarbonization organization getting to scale without tapping utilities in some way as a channel.

2. And yet…. utilities don’t know much about what is on the other side of their meters… among other things, C1.5 aspires to help utilities better know and engage their customers which arguably may have broader business value to them.

3. While utilities do not tend to move fast… the electric grid has been called the most complicated machine every built… and an incredible amount of innovation will need to happen over the next couple of decades in order to more tightly integrate changes in the built environment that impact electricity demand with changes in the grid associated with the delivery of more and more renewable energy.

Additional Resources (still need to fix a few links)

Transforming_NYC_Buildings_for_a Low-Carbon_Future No need to read every word…. But pages 23 - 31 of “The Technical Working Group” (TWG) report should have been titled: “Meet NYC building stock data” – everybody should have a feel for basic breakdowns about the number of big buildings vs little buildings; old buildings vs new buildings, multifamily buildings vs. commercial buildings, etc…. And that is all here.

Low_Carbon_Multifamily_Retrofit_Playbooks Drawing on TWG report learnings, breaks the NYC MF sector into about 5 repeatable typologies with further details on the finite number of upgrade packages that apply to each one to get to deep decarbonization. Simple, but not easy. Also worth noting that the primary authors of this report had an agenda for pushing deep envelope upgrade work, first, including adding wall insulation in all cases. We may see many owners choose to allocate resources in different ways in order to most optimally address decarbonization and climate justice goals.

Retrofit_Technology_Primers Short primers on a variety of different retrofit technologies that were written by SWA staff.

Improving_Ventilation Primer on how to fix most common ventilation systems in NYC MF buildings… because 99% of them don’t do what they are supposed to do…. Not an energy/carbon thing as much as an indoor air quality thing.

Retrofitting NYC’s Multifamily Buildings (with heat pumps) A nicely illustrated and packaged primer by UGC

Decarbonizing Homes Its about more than carbon. Bomee’s take on how beneficial electrification can improve health in low income communities.

Recognizing the Benefits of Energy Efficiency in Multifamily Underwriting A little outdated (although sadly not much has changed since it was published in 2012)…not to mention it might have been the first very significant thing Bomee and MZ did together! The 6-page Executive Summary is worth a read…. Human energy auditors are statistically pretty terrible…. But even crude data analysis can help a lot.

Solar PV Video trainings covering the basics of this technology along with some deeper details – all focused on bigger building applications (mostly multifamily). The first one “Solar 101” is worth everybody watching. (TO BE ADDED AS A RESOURCE POST SWA CLOSING)