Tech Notes: Accessible Parking in Precast Garages

When designing accessible parking spaces, it is important to remember that the slope of the ground surface for the entire parking space and adjacent access aisle must not exceed 2% in any direction. We frequently see noncompliant slopes at accessible spaces, especially when the ground surface is asphalt or permeable pavers.  The slope along the perimeter of spaces at curbs or gutters is frequently more than 2% at up to 5%, which requires careful detailing and planning on the part of the architect, civil engineer, and on site contractors to ensure that a compliant slope is achieved at the accessible parking spaces. At parking structures and precast garage systems, we have found that important details and coordination needed to achieve compliant ground surface slopes are often overlooked.

 

Ground surface slopes at walls or parapets often exceed 2%, (blue highlight) resulting in noncompliant slopes at the heads of accessible parking spaces.

In parking structures, it is common for an area along the perimeter of the slab (adjacent to walls or parapets) to slope in excess of 2% for drainage purposes. In some cases, this slope is embedded into the precast system. As a result, accessible parking spaces must be located away from the sloped edges during the initial design phase.

In other cases, noncompliance results from the application of a cast in place (CIP) wash applied to the top of the precast slab. In the detail shown below, note the slope condition at the CIP topping. The wash is often indicated only in section details on the precast drawing set, making it easy to miss if designers are not specifically looking for how these details affect accessible parking spaces. The entire project team involved in the design and/or construction of the garage must be made aware of where accessible parking spaces are located and understand the specific slope requirements to ensure that details are properly coordinated.

The cast in place topping results in a slope of more than 2% at 8.33% at the head of the accessible parking space in this precast garage.

 

Once the garage is constructed, it is nearly impossible and very costly to fix noncompliant slopes at the head of accessible parking spaces. In some garages, we have been able to solve the problem by shifting the striping at accessible parking spaces. This results in the steeply sloped ground surface being located fully outside of the parking space and access aisle. The problem is that this solution is dependent upon whether the spaces can be shifted without compromising the minimum required width of the drive aisle or obstructing access to other parking spaces.

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Trends in Healthcare: Nurse Call Devices

“Trends in Healthcare” is a recurring series that focuses on exciting new designs and technologies we’re seeing in healthcare projects and provides best practices on how to ensure that these latest trends are accessible to persons with disabilities. We build on the wealth of knowledge we gain from working with healthcare design teams, construction crews, and practitioners to provide practical solutions for achieving accessible healthcare environments.


According to the U.S. Centers for Disease Control and Prevention (CDC), falls account for 3 million injuries treated in emergency rooms, 800,000 hospitalizations, and 28,000 deaths each year in the U.S. One in five falls cause serious injuries such as concussions/traumatic brain injuries and hip fractures. Not only is this a public health concern, it is extremely costly. According to the CDC, medical costs directly related to injuries resulting from falls totaled more than $50 billion in 2015.[1] Within hospitals and long-term care facilities, effective implementation of interventions and design strategies to reduce patient falls are key to increased patient safety and decreased medical costs. However, it may not be possible to eliminate patient falls altogether, so features like a properly installed nurse call system can be life changing.[2]

Accessible Nurse Call Stations

Most state and local standards and regulations require nurse call devices in each public toilet room and within inpatient bath, toilet, and shower rooms.[3,4] Where provided in spaces required to be accessible, the nurse call device must also be accessible. An accessible nurse call device is one that meets the following requirements:

  • All operable parts, including call reset switches, are within accessible reach range (15-48″ AFF);
    • NOTE: Determining compliant mounting height requires coordinating with the location of operable parts on the specific model used.
  • Operable parts do not require tight grasping, pinching, or twisting of the wrist to operate; and
  • Operable parts can be activated with no more than 5 pounds of force.

The location of operable parts differs between models of nurse call devices. It is important to determine mounting location based on the specific model of device being used.
Models shown (clockwise, L to R): Intercall Emergency Stations; Becas BeSmart Nurse Call System; Cornell Visual Nurse Call System

While these criteria appear straightforward, proper placement of nurse calls can become complicated when coordinated with minimum grab bar clearances and additional requirements under FGI, NFPA 99, NFPA 70, Ul 1069, UL 2560, and other local codes.

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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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