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Tag: Existing Building Performance

Is It Too Late to Start On My Local Law 87 Compliance for 2019?

Before there was a Green New Deal in New York City, there was Local Law 87, which requires an energy audit and retro-commissioning report to be conducted and filed every 10 years. Yes, it still applies, and yes it will help you to understand the most cost-effective retrofits and upgrades to target for compliance with the city’s new energy efficiency requirements. Thanks for asking!

The question we get most this time of year from owners in NYC is, “My building is due for LL87 compliance this year, is it too late to start?!”

Image of Commercial BuildingsAs spring arrives, building owners often realize that time is quickly running out and this is the year that they must submit their building. Compliance with NYC’s LL87 (Local Law 87) can be overwhelming and hard to navigate but we are here to help.

Not sure if you have to file?  Check here.

LL87 requires that a building undergo an energy audit and retro-commissioning of major mechanical equipment. Keep in mind that it takes time to perform the inspections and testing. In fact, your best bet is to start in the year before your deadline, leaving yourself plenty of time for planning, budgeting, and implementing any corrections that may be required.

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What Does NYC’s Climate Mobilization Act Mean for Building Owners?

Image of Existing Buildings in NYC

On April 18th, Introduction 1253-2018 was approved by the New York City Council along with several other major pieces of legislation as part of a Climate Mobilization Act. The Urban Green Council describes it as “arguably the most disruptive in our lifetime of the NYC real estate industry.” We agree. While it will take some time to more precisely gauge impact across the industry, here is an initial primer.

Update: On May 18th Intro 1253 was passed into law as Local Law 97 of 2019.

Context

Previous building energy legislation in NYC has focused primarily on providing the market with access to information in the form of benchmarking and audits. In response to increasing demands for more urgent climate action, this new local law will actually require energy performance levels – and significant retrofits in some cases – in most existing buildings over 25,000 square feet between now and 2030 and deeper reductions beyond 2030.

How Does Local Law 97 Work?

The law establishes targets for carbon-emissions intensity per square foot for buildings based on occupancy class. For instance, multifamily buildings, office buildings, schools, and storage facilities will have different intensity targets. Mixed-use buildings will have their targets set based on a weighted average of their different spaces. Across all segments, these targets will get ratcheted down over time. Building on the type of data submitted as part of annual benchmarking, all tenant and owner energy used at a particular building will be converted to carbon intensity per square foot.

Starting in 2024, buildings will be fined on an annual basis for carbon footprint that exceeds their targets. Based on their performance today, approximately 20% of buildings exceed the 2024 – 2029 targets while approximately 75% of buildings exceed the 2030 – 2034 targets, according to the City Council’s press release. As an alternative to this performance-based framework, rent regulated multifamily buildings with at least one rent stabilized apartment will be required to implement a prescriptive list of upgrades by 2024. These upgrades include indoor temperature sensors providing feedback to boilers and apartment thermostatic controls.

What Will It Mean to the Market?

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Buildings to Cool the Climate

The Intergovernmental Panel on Climate Change (IPCC), viewed as the most credible source of climate change research, issued an alarming report on October 2018 removing all doubt – absent aggressive action the atmosphere will warm up by as much as 2.7 ° F above preindustrial levels by 2040, inundating coastlines and intensifying droughts and poverty. The significance of this report is that the effects of climate change will occur in our lifetime.

The building construction sector has a critical role in drawing down carbon emissions by 2040. As nations all over the globe tackle operational emissions from buildings, we must now address our total emissions impact.

 

graph of estimated cumulative carbon emissiongsi

Life-cycle emissions resulting from buildings consist of two components: operational and embodied. A great deal of effort has been put into reducing the former as it is assumed to be higher than the latter. Studies have revealed the growing significance of embodied emissions in buildings, but its importance is often underestimated in energy efficiency decisions.

According to the Embodied Carbon Review 2018 by Bionova Inc, embodied carbon is the total impact of all the greenhouse gases emitted by the construction and materials of our built environment. Furthermore, during their life-cycle, the same products also cause carbon impacts when maintained, repaired, or disposed of.

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Benefits of Water Metering and Water Monitoring

Water monitoring can quickly become a building owner’s best friend. The high cost of water bills can often overshadow the cost of fuel and electricity bills, but ownership and management often believe that the price of their water bill is simply something to deal with. Many building owners pay the water bill for the entire building directly to their local utility without being aware of what’s going on inside their building or what they’re actually paying for. After all, without water monitoring, how would they know?

Water monitoring can impact an owner’s bottom line due to the high costs of leaks, which are more pervasive than you’d think.

Types of Leaks

Image of toilet with components labeledWhile any water fixture can contribute to leaks and high water bills, toilets are typically the worst offenders. In toilets, rubber flappers can wear out, a flapper connected to the flush handle can have an incorrectly sized chain interfering with the seal, float mechanisms on the flush valve can be set too high causing the water level to go just above the overflow tube, or there can be tenant tampering.

Showers and sinks can also start leaking at any time. While typically at much lower capacities, these leaks can actually be easier to detect. By monitoring the water consumption in a building and observing hourly usage overnight, you can identify patterns that can quickly indicate a leak, eliminating the need to visually inspect all water fixtures in a building to determine the cause.

Cost of Leaks

The idea that a single leak can last for an entire year may seem unreasonable, though the sad truth is many leaks can go undetected and/or unreported. To put water leaks into perspective, the chart below from the NYC DEP details the potential extent of leaks and their costs on a daily and yearly basis:

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Establishing Moisture Control in Multifamily Buildings

Most of us are familiar with the feeling of a humid apartment after taking a hot shower. Some of us kick on an exhaust fan, perhaps un-fog the bathroom mirror, or even open a window to get the moisture out. Domestic moisture generation—moisture from human activity—is a major factor driving the humidity levels in our residential buildings, especially in super air-tight, Passive House construction. Before diving into just how much of an impact domestic moisture has in our buildings, let’s first look at average daily moisture generation rates of a typical family of three[1]:

  • breathing and transpiration—6 to 9 pounds of water vapor/day;
  • 10-minute shower in the morning for each individual—3.6 pounds of water vapor;
  • cooking fried eggs and bacon for breakfast—0.5 pounds of water vapor;
  • cooking steamed vegetables with pasta for dinner—0.5 to 1.0 pounds of water vapor; and
  • one small dog and a few plants around the house—0.5 pounds of water vapor/day

This brings the daily total to 11.1 to 14.6 pounds of moisture generation per day, or about 1.5 gallons of liquid water.

Where does all of this moisture go? In a typical code-level apartment building with moderate to high-levels of air leakage, water vapor has two year-round exit pathways: exfiltration through the façade and dedicated kitchen or bathroom mechanical exhaust. Additionally, in the summer, moisture is removed via condensate from the cooling system.

Let’s now put this in the context of a highly energy-efficient apartment with very low levels of air leakage (about 5 to 10 times less than the code-compliant unit), and balanced ventilation with energy recovery. The first means of moisture removal, façade exfiltration, is virtually non-existent given the building’s superior air-tight design. Next is mechanical exhaust ventilation in the kitchens and bathrooms. Because the unit has balanced ventilation and energy recovery, the exhaust air stream in a Passive House project typically passes through the energy recovery core. Depending on the core selection, a large percentage of the interior moisture may be retained in the apartment air despite the constant mechanical air exchange.

There are two basic types of cores:

  • Heat recovery ventilator (HRV) in which a certain percentage of sensible heat is recovered (transferred from the exhaust air stream to the supply air stream) while no moisture is recovered.
  • Energy recovery ventilator (ERV) in which a certain percentage of sensible heat and a certain percentage of moisture in the air is recovered.

To fully understand this issue, Figure 1 breaks break down the moisture-related pros and cons of ERVs and HRVs in the context of a high-density, Passive House building.

  ERV HRV
Pros Summer – prevents high exterior air moisture load from being supplied to interior air; cooling loads are minimized Winter – flushes high internal moisture load out of building; humidity levels reduced
Cons Winter – if internal moisture generation is high, interior moisture load is not flushed out of apartment; humidity levels increase Summer – allows exterior air moisture load to be supplied to interior air: cooling loads increase

Figure 1. Moisture related pros and cons with ERVs and HRVs in high efficiency, airtight construction

 

Traditionally, the key factor in deciding between an ERV or HRV for a high-efficiency building has been the project’s climate. However, as internal moisture loads begin to exceed exterior moisture loads in high-density projects, the decision between ERV or HRV must be looked at more closely for each project regardless of climate.

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ERV + AHU?

Everyone pretty much gets that continuous (or very frequent) ventilation is necessary in high-performance homes. And – at least in theory – most people get why balanced, heat recovery ventilation is better (than unbalanced and/or without heat recovery). But the devil’s in the details.

A couple years ago we started an R&D project with funding from DOE’s Building America program, and one of the first steps was interviewing several developers about ventilation (single- and multi-family residential, mostly on the East Coast). For none of these developers were HRVs or ERVs standard.[i] They all had some experience with ERVs, however, and when asked about these experiences the word “nightmare” came up shockingly often.

The ERVs on the market now can certainly work well in the right application, but we see problems more often than not. One of the biggest challenges is trying to add ERVs on to central heating/cooling systems in homes. Most ERVs aren’t really designed for this, and here’s what we see:

  • Ducts connected to the wrong places! Outlet and inlet ducts get reversed, or the supply air from the AHU getting exhausted (sad how often this happens).
  • ERVs are attached to supply and/or return trunks of the AHU. Unless the AHU fan is running constantly (or whenever the ERV is turned on), outdoor air comes into the AHU and is sucked right back out the ERV exhaust.
  • If the AHU fan is turned on, the relatively small fans in the ERV can’t successfully compete with the big AHU fan. People don’t get the ventilation flow rates they want and/or the flows are very unbalanced.
  • AHU fans can use A LOT of electricity. Hundreds of Watts is common – I’ve measured over 1 kW (though this is changing – more below).

Even if installers follow manufacturer instructions for attaching ERVs to AHUs, they could still end up with low flows, unbalanced flows, or high electricity consumption. Through this DOE R&D effort, we’re trying to do better.
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Does Your Exhaust Fan Suck? Part 2

If you recall from Part 1 of this article written back in September, we discussed why exhaust fans often don’t operate as they are intended. Now, let’s discuss how to rectify these issues. First, we need to understand that all fans are not created equal. To do this, SWA participated in a “blind” study that analyzed a number of today’s common exhaust fans. The study emphasizes the importance of fan selection. With this understanding, we will then discuss solutions and best practices for installing bathroom exhaust ventilation.

The “Blind” Study

To get a comprehensive performance dataset for a number of exhaust fans, the Riverside Energy Efficiency Laboratory (REEL) was engaged for a “blind” study. REEL is the HVI/ESTAR neutral, third-party testing facility. In total, 7 multi-speed fans, 7 single speed fans, and 6 low-profile fans from six manufacturers were sent to REEL without manufacturer markings. In general, ten-point airflow tests were conducted on each fan. Testing adhered to standards used in the industry, namely, ANSI/AMCA Standard 210 and HVI Publications 916 and 920, where applicable. While the dataset is extensive, this paper focuses on the 50, 80, and 110 cfm ventilation rates, as these are the most common specified fan speeds for bathrooms. These fan curves show the relationship of airflow that will be delivered at various static pressures of the duct system.

Figure 1 shows fan curves for single speed fans that were tested. The units are rated for 80 cfm unless noted otherwise in the legend (two are rated for 70 cfm and one for 90 cfm). While all of these fans performed in a similar manner, would it surprise you that two of the fan curves in Figure 1 are for exhaust fans that use DC motors? People often assume that all fans using DC motors are the same and result in constant airflow for a range of static pressures (let’s say up to 0.4” w.g.).

Figure 1

Figure 1. Performance Data for Single Speed Exhaust Fans

It is clear in this data (Figure 1) that flow rates decrease rapidly when static pressure rises over 0.3” w.g., as it often does in real world installations. Oh, are you still wondering which two fans have DC motors? It is actually SS-05 and SS-06. A bit surprising, isn’t it?

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Here’s What the Clean Energy DC Act Means for Existing Buildings in the District

Mayor signing legislationDistrict of Columbia Mayor, Muriel Bowser, signed a landmark piece of legislation known as the Clean Energy DC Omnibus Amendment Act this past Friday. With the mayor’s signing, Washington, DC becomes one of the first jurisdictions in the country with a binding, comprehensive law aimed at reducing greenhouse gas emissions. “It allows us to make significant improvements to the energy efficiency of existing buildings in the District,” Mayor Bowser said at the signing ceremony.

The new law has several sections which will impact the buildings in which DC residents and businesses live and work. In this post, we’re going to focus on Title III of the Clean Energy Omnibus Amendment Act, which is designed to make the city’s existing buildings more efficient.

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Looking for a Fast Payback by Installing a Dedicated Domestic Hot Water System? You May Want to Look Elsewhere

Installing a dedicated domestic hot water (DHW) plant is a common energy conservation measure (ECM) in the New York City multifamily market. According to Local Law 87 data, approximately 80% of the audited multifamily floor area uses steam heating boilers to produce domestic hot water.[1] A recent SWA analysis of data from steam buildings with tankless coils that implemented this ECM suggests that auditors may want to think twice about recommending this measure widely.

Two unsupported arguments are typically made in favor of installing a dedicated DHW system.

  1. A new condensing boiler or water heater (we will just say “water heater” here for simplicity and to distinguish the dedicated system from the heating boiler) will operate at a very high efficiency.
  2. Scotch marine steam boilers are inherently inefficient and are plagued with high standby losses. Large Scotch marine boilers fire to meet small DHW loads, and correctly sizing a new dedicated water heater will eliminate short cycling.

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Linkageless Burner Retrofits for Steam Boilers

Going Beyond Carburetor Technology in the NYS Market

Fun Fact #1: Space heating and domestic hot water generation represent two of the greatest energy end uses in New York State.

Fun Fact #2: More than 70 percent of all New York City buildings utilize steam for space heating.

Background

The clear majority of the distribution systems in these NYC buildings are supplied by high mass steam boiler plants. Digging down a bit further, it is important to note that the most common air:fuel control for these boilers is a mechanical linkage that connects a single servo motor to both the combustion air damper and the fuel control valve(s). We know that adjusting one part of the linkage’s movement affects fuel and air rates elsewhere in the range, making accurate adjustment difficult. We also know that modern linkageless controls use separate servo motors to operate the fuel control valves, combustion air damper, and (in some cases) the flue damper, allowing for finer control.

mechanical linkage system and linkageless system

In fact, SWA recently completed a demonstration study (partially funded through NYSERDA’s Advanced Building Program) to evaluate linkageless burner retrofits on two buildings with respect to energy savings and carbon reductions, as well as qualitative or non-energy benefits. The retrofit materials were funded by Preferred Utilities Manufacturing Corp. of Danbury, CT, who also provided manufacturer’s technical support. The study also focused on quantifying the seasonal efficiency of intermediate-sized, high mass steam boiler plants, which had not previously been studied. The demonstration addresses this gap in the industry’s knowledge.

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