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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 labeled

Source: http://michaelhannan.co/wp-content/uploads/2018/08/diagram-of-digestive-system-in-hindi-toilet-bowl-parts-tank-repair.jpg

While 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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The Top 10 Party Walls Posts of 2018!

2018 has been a year to remember for SWA’s Party Walls blog. Our consultants have shared their passion for high performance buildings by recounting stories from the field and providing information, new findings, and best practices to improve the built environment.

Whether discussing topics based in New York City or Southeast Asia, here are our fan favorites from 2018…

Collage of blog images

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Reducing Air Leaks in Multifamily Buildings (and why you should care)

If there was ever a silver bullet when it comes to best practices in multifamily buildings, air sealing would be it. Compartmentalization – or air sealing each unit to prevent infiltration between units and to the exterior – addresses many major issues we see in buildings.

Better HEALTH

  • Air sealing is the best strategy to keep pests out and limit their movement within a building.
  • Air carries a lot of moisture, so eliminating air leaks helps keep buildings dry and reduces the risks of mold and water damage.
  • Compartmentalization prevents contaminated air from garages, basements, attics, and other undesirable sources from entering living spaces.

Improves COMFORT

  • Air sealing reduces drafts and eliminates hot and cold spots.
  • Limiting air transfer from one unit to the next reduces transmission of noise, smoke, and odor between units.

Wastes less ENERGY

  • Air sealing lowers heating and cooling bills maintaining a more consistent indoor temperature.
  • Compartmentalization improves the performance of ventilation and mechanical systems by limiting pathways for stack effect – the force of warm air from low to high – to occur in larger buildings.

How to Air Seal Multifamily Units

It’s important to remember to create a complete air barrier around the entire cube of a multifamily unit, not just to the exterior – any and all penetrations need to be sealed.

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ENERGY STAR New Construction Certification Programs for Multifamily to be Combined

ENERGY STAR MF LogoCurrently, to receive ENERGY STAR® certification for multifamily new construction, you would get your certification through the ENERGY STAR Certified Homes program or the ENERGY STAR Multifamily High Rise program. This may change by early 2020. According to the Environmental Protection Agency (EPA) in a recent statement, multifamily will soon have a single program, rather than splitting them across the Certified Homes program and the Multifamily High Rise program.

“To better serve the multifamily sector, EPA is in the process of creating a single ENERGY STAR multifamily program by merging the current requirements and adopting the most appropriate from each.”

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