Building Capacity

Client Health and Autonomy, Building Durability, and Cost Control were Key Drivers for Sound Mental Health’s LEED Platinum Housing Project in Seattle, Washington

Kathleen O'Brien interviews project designer Chirstina Bollo.

 

 

Kenyon House is an 18-unit two-story affordable housing project for previously homeless people with disabilities and fragile health. The project was developed by Housing Resources Group, AIDS Housing of Washington, and Sound Mental Health, all 501©3 organizations. O’Brien & Company provided initial rating, technical assistance, field application assistance, and performance testing and site verification of the envelope installation.

The project was the first project in the State of Washington to attain LEED for HomesPlatinum certification for affordable housing and only the second in the United States. It was completed in 2008 and featured in GreenBuild 2009’s LEED Project Showcase. According to Owner Sound Mental Health’s Trish Blanchard (Chief Clinical Officer), the agency is “grateful for this beautiful and sustainably built project and the partnerships that made it possible. Kenyon House provides supportive housing for some of the neediest and hardest-to-house in our community.”

Christina, you were the Project Designer with SMR Architects on the Kenyon House Project. What was your experience with “green” design prior to this project?I was lucky enough to study at the University of Oregon with John Reynolds and Alison Kwok from 1999 to 2002. While there I was involved with the Agents of Change Vital Signs Case Study Project, which included investigating actual buildings, conducting post-occupancy surveys, and developing case studies based on real world results. I’ve been interested in sustainability from the beginning.

It shows! You managed to achieve the highest LEED rating on the project. Was that planned from the beginning? Yes and no. From the beginning, I was referring to the LEED for Homes checklist to make sure the design was meeting the standard. But the owner was not planning to get the project certified. That changed when the non-profit developer found funding for certification. It was actually pretty late in the game, but because I’d been using the LEED checklist all along the project was actually able to do pretty well.

I’ll say. Was LEED the driver then for your decisions? I would not say that. It informed   but did not drive the sustainability decisions. Thinking about the owner’s goals and the residents needs was truly what drove them. For the owners, it was important to design a building that would last 50 years -- the term of the funding requirement. So for example, we detailed the windows so they can be replaced without tearing the building envelope apart. We used a fiber cement rainscreen for a more durable enclosure and focused on durability throughout. Of course the other big issue for the owner is cost of operating the facility. So saving energy and water was also a priority. All of this matches very well with LEED for Homes.

And what about the residents?Thermal comfort and good indoor air quality are always important in a residential setting, but especially in this one, where the occupants are in fragile health. I will say that LEED for Homes is much more suitable for this type of project. One concern with the non-residential LEED standard was its smoking prohibition. In a situation like this, such a ban would actually encourage surreptitious smoking, perhaps causing fires. Continuous ventilation was obviously key.

Any hiccups getting into LEED so late?We had a few stressful moments. O’Brien & Company had to submit a CIR for the paper-faced drywall already installed for the tub enclosure. They determined the drywall could meet the performance requirements, especially since we had the contractor apply a primer to the board. But probably the most challenging aspect of implementing LEED so late in the game was our needing to solicit signatures for accountability forms from consultants who had been off the project for quite some time. We got it done, but it was daunting.

How did your contractor feel about the added LEED performance requirements? Our contractor Walsh Construction was pretty enthusiastic about it. They saw it as an opportunity to learn advanced sealing techniques and committed to implementing them on all of their projects as a matter of practice.

Besides LEED performance, what else about the project meshes with the goal of sustainability? Social equity is an important aspect of sustainability. For the owner, above all else was the desire to create an autonomous, independent living situation for the residents, while fostering interaction between them and staff. The lobbies and central staircases were designed to force circulation past the case workers’ office. Yet, the studios are totally self-sufficient. The backyard was deliberately set aside for vegetable gardens maintained by the tenants. So it’s a nice mix of community and privacy.

You mentioned community. How do the neighbors feel about the project?Well actually the project addressed a safety problem the neighborhood was dealing with. The zoning called for the long side facing E-W (perpendicular to the street). This was terrible orientation for passive heating and cooling (as well as daylighting). The site’s original configuration also made for a pass-through for “hooligans.” Turning the building, so the long side now faced SW (with the front facing S), helped provide a buffer against such straying and entirely changed the building’s energy performance potential for the better. It was definitely a win-win and a no-brainer getting through to the city. This configuration also made more space for the tenant’s backyard garden.

Looking back, how do you feel about the project now? I am very happy with it. In fact, I’m finding it difficult to leave it behind! The landscaping budget was pretty tiny. So for a while it was a very fancy building sitting in a bunch of mulch. I’ve been involved with a series of volunteer landscaping projects for the front yard. And now that the Seattle Department of Transportation has started allowing it, I’m hoping we can do something fun with the parking strip. It gets great light all year round.

Christina Bollo designs environmentally and socially sustainable homes for homeless people and people with special needs. She received a Master of Architecture degree from the University of Oregon and is a registered architect in Washington State. She is the chair of the Seattle Pedestrian Advisory Board and a member of the national board of Architects/ Designers/ Planners for Social Responsibility.

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How do you optimize a forced-air system to maintain a green home? Alistair Jackson, LEED AP for Homes Rater Responds: Part 4: MECHANICAL VENTILATION

If not installed or maintained properly, forced-air heating and cooling systems can perform poorly, creating air quality problems and unnecessary expense. To optimize a forced-air system, you need to design or refine it to prevent leaks and pressure imbalances, protect it properly during construction (or make sure the ductwork is clean and sound), and use the right filter.

The performance spec of the heat (or cooling) source is also important, but it is critical to address the distribution system first before investing in better furnace and air handler performance. This article is the FINAL of four focused on optimizing forced-air systems on the topics of Distribution, Filtration, Heat Source (and Controls), and Ventilation.

Whether in a new house or an existing home, mechanical ventilation is an important component of indoor comfort and building durability. Here in Washington, codes have required it for several years, but that doesn’t necessarily mean the ventilation system in a home is effective.

This is another system that is worth having tested by a qualified contractor to see if it is over- or under-performing. A system that is under-performing (provides less airflow than recommended) may not provide adequate fresh air or remove enough moisture from the home. A system that is over-performing (providing too much airflow) will increase energy consumption, as heating system has to heat or cool the additional volume of  air.

The ventilation performance requirements of the IRC 2009 (and the current Washington Residential Code) are consistent with ASHRAE 62.2-2007, a recognized national reference standard, and a great performance benchmark even for a project that isn’t covered by the code. The intent of this standard is to ensure adequate air changes in the home, based on size and occupancy load. It requires mechanical ventilation with dedicated outside air inlets in new construction to increase the likelihood of effective ventilation.

For existing homes, it should be noted that mechanical ventilation becomes increasingly important as the building envelope becomes more air-tight. If a blower door test gives a result of ≥7 ACH@50, the focus should be on reducing envelope leakage rather than adding mechanical ventilation. This test result is roughly equivalent to 0.35 nACH or about one air change every three hours. With this much leakage in the envelope, the house will experience more than enough ventilation through the natural convection caused by “stack effect” as well as those induced by the influence of wind on the structure. But if your envelope weatherization efforts have brought envelope leakage substantially below this level, adding effective mechanical ventilation is a top priority.

Let’s assume we’re talking about a project that has successfully upgraded the building envelope to something less than 4 ACH50. A common practice in forced air homes is to integrate a mechanical ventilation system into the forced air system; a logical approach since you already have a system of ducts to deliver air to all the living spaces. This is called a “Central Fan Integrated System (CFIS)” – Imagine that. It is a straightforward solution that can be properly implemented for around $500 as long as your distribution ductwork is clean and sound and there’s easy access for a duct run from your air handler to an exterior wall, away from other exhaust outlets.

In its simplest form, this approach consists of a duct into the return side of the air handler, drawing fresh air into the system whenever the air handler fan runs. The problem with this approach is that the ventilation rate is totally dependent on how much the air handler runs. So on the coldest days (or the warmest days in a cooling-dominated climate) you get the greatest ventilation. On these days, the outside air also needs more conditioning to meet the indoor set-point temperature – so that means more heating (or cooling) energy; a recipe for higher energy bills.

                                      

This can be mitigated by adding a “fan cycler” – a control box connected to a mechanical damper in the fresh air duct. See the mechanics of an AprilAire fan cycler  in the photo at left. The fan cycler opens and closes the fresh air duct and monitors how much time the fan runs with the duct open. On cold days, it will close the fresh air duct once the ventilation air volume for a given period has been reached. On mild days, when heat (or cooling) demand is low, it will also switch on the air handler fan to circulate fresh air to meet the ventilation requirement. The disadvantage of this action is that it uses the large air handler fan (and associated electrical consumption) to circulate a relatively small amount of fresh air. If your air handler includes an efficient, variable speed fan this impact is significantly reduced. Aircycler provides an interactive  schematic showing the airflow.

 

Another approach that reduces fan energy is to tie the Fan Cycler to one or more exhaust fans and use these fans to pull outside air through the ducts when the air handler is not running. Energy Star labeled fans from Panasonic and others use a fraction of the energy of a typical air handler fan. I’m not personally convinced this solution provides good outside air distribution but it may be worth further exploration.

Energy (or heat) recovery, where energy from the stale exhaust air is used to pre-condition the incoming fresh air, can also be integrated into this approach. Typically, the air handler fan of an HRV or ERV is not large enough to effectively circulate fresh air through the large, forced air duct system, resulting in inadequate distribution and mixing of outside air. It is better to integrate the ERV/HRV with a fan cycler and use the furnace air handler fan, (Venmar AVS used to sell a passive  HRV unit called the Enerflo, that offered all this in one convenient unit, but I’m not sure this product is still available – comment if you know differently!).

You can also install small diameter, dedicated ductwork for the ventilation air distribution. Either approach will involve increased installation cost and control complexity (see the photo). In simple payback terms, this probably only makes sense in very cold or hot climates.

 

IMPORTANT NOTE: Any CFIS system requires proper commissioning by a qualified technician to ensure it is performing properly and delivering the required rate of ventilation in a range of conditions. Your HVAC contractor may be able to provide this service, or you may choose to use an independent contractor such as those listed with Home Performance Washington, RESNET, Building Performance Institute (BPI), National Comfort Institute Certified Contractors. 

Alistair Jackson, LEED AP, CSBA is Principal in Charge of O’Brien & Company’s Residential Technical Services, and is a LEED for Homes, Energy Star and Built Green Verifier, LEED for Homes Faculty and ARCSA certified Rainwater Harvesting designer. Alistair is a frequent contributor to the Building Capacity Blog and was also a major contributor to the Northwest Green Home Primer.

Did you enjoy this article?  You might also like these Building Capacity Blog articles:
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 1
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 2
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 3
Interview with LINC’s Maria Elena Marquez-Brookes
Creating Effective Energy Efficiency & Conservation Strategies Part 1
Cracking the Energy Code: What Will It Cost?
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How do you optimize a forced-air system to maintain a green home? Alistair Jackson, LEED AP for Homes Responds: Part 2: FILTRATION

If not installed or maintained properly, forced-air heating and cooling systems can perform poorly, creating air quality problems and unnecessary expense. To optimize a forced-air system, you need to design or refine it to prevent leaks and pressure imbalances, protect it properly during construction (or make sure the ductwork is clean and sound), and use the right filter.

The performance spec of the heat (or cooling) source is also important, but it is critical to address the distribution system first before investing in better furnace and air handler performance. This article is the SECOND of four focused on optimizing forced-air systems on the topics of Distribution, Filtration, Heat Source, and Ventilation.

Some are inclined to believe that forced air systems are more of a cause of air quality problems than a solution. However, one of the advantages they offer is the ability to continuously filter the re-circulating indoor air as well as the outside ventilation air (in a central fan integrated system). While filtration shouldn’t replace efforts to reduce source contaminants, this can be a real bonus to homeowners who have pets (including small children :), live in areas with a lot of particulates in the outside air or have a need for highly-filtered indoor air.

Filters in forced air systems are generally (and preferably) located in the return trunk immediately upstream of the air handler, though sometimes they are located at central return grilles. An important consideration here is accessibility – filters must be cleaned or changed according to manufacturers’ instructions to maintain performance and minimize wear and tear on the equipment. So they should be easily accessible to the homeowner and the access door should be air-sealed in such a way that it will reseal easily and effectively, even after it’s been opened multiple times.

If the air handler is in a garage or mechanical closet, that’s probably a good place for the filter, but if it is in an attic, crawl space or other location that’s hard to reach installing high-efficiency 1-inch filters at the central return grilles might increase the likelihood they’ll get changed regularly. Clogged filters will reduce the air flow through the system, affecting comfort and energy efficiency and potentially increasing wear and tear on the system.

Use the highest efficiency filter appropriate for the system, preferably a filter with a MERV rating of 10 or higher. MERV, or Minimum Efficiency Reporting Value, is a simplified expression of the effectiveness of a filter at removing particles of different sizes from the air stream flowing through it. What you need to know is that MERV is a scale from 1 to 16, that 10 and above are considered to be high-efficiency, and that the non-woven, fiberglass filter that was supplied with your furnace (and may still be in there . . .) probably wouldn’t even get a MERV of 1! (Such filters are installed to protect the air handler from large dirty objects, not your respiratory system from small ones.) If you want more details on what MERV is really all about, visit the National Air Filtration Association website.

If you are upgrading the filter in an existing system, bear in mind that for a given surface area of filter, the higher the MERV rating, the greater the pressure drop across it. One inch filters above MERV 11 may cause sufficient pressure drop to significantly affect the performance of an existing system. If you are upgrading the air handler, the fan/blower spec can be altered to accommodate this, but if you’re adding more efficient filtration to an existing air handler it may be worth increasing the surface area of the filter. This typically means switching to a thicker, pleated filter (perhaps 3” or 4”) which may create an installation challenge in the existing sheet metal. However, if the upgrade also includes full duct sealing and insulation, the reduced losses in the system may offset the reduced flow from a moderate improvement in filter performance. Measuring the pressure drop across the filter and in various parts of the system will provide useful data to support good design decisions. Add a manometer (such as the JMW digital manometer pictured above,  and the know-how to use it to your toolbox, or find an HVAC balancing contractor or home energy specialist to assist you.

Make sure the homeowner understands the maintenance requirements of medium- or high-efficiency filters, the benefit of fulfilling those requirements, and the downside of not doing so. The photo to the left shows two filters, one new and one with just a few months of wear that is quite clogged.

Filters with the lowest first cost, such as one-inch (1”) pleated media, require regular replacement (four times per year), amounting to considerable cost over time. Four-inch pleated media filters are now commonly available. Though they cost more individually, they generally require less frequent replacement (so have a lower lifecycle cost) and cause less pressure drop than a 1” filter of similar cross-sectional area. For systems in big homes that move large volumes of air, high efficiency bag-type filters (some of which are washable) may be a worthwhile consideration.

Although electrostatic air filters enjoy a PR buzz, green designers generally don’t recommend them. To maintain their performance, they should be cleaned as often as once or twice per month, and most homeowners are not willing to keep that schedule up. When they’re dirty, their filtration performance drops dramatically, and they may generate and introduce ozone—a significant respiratory irritant—into indoor air stream.

Next week we’ll be looking at heat sources in a little more detail.

Diagnostic HVAC Resources: To find a qualified Home Performance Testing contractor, check out websites for Building Performance Institute (BPI) or RESNET. If you are located in Washington see Home Performance Washington or Northwest Energy Star. To locate a Balancing Contractor, see National Comfort Institute Certified Contractors.

Alistair Jackson, LEED AP, CSBA is Principal in Charge of O’Brien & Company’s Residential Technical Services, and is a LEED for Homes Rater, LEED for Homes Faculty, Energy Star Verifier and Performance Tester, ARSCA Accredited Professional, and Built Green Verifier. Alistair was also a major contributor to the Northwest Green Home Primer where much of the information for this article originally appeared. It has been expanded upon for this publication.

Did you enjoy this article? You might also like these Building Capacity Blog articles:
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 1
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 3
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 4
Mechanical Systems and Fuel Choices for the Warming World
Cracking the Energy Code: What Will It Cost?
Passive House: A Bit of Overkill

How do you optimize a forced-air system to maintain a green home? Alistair Jackson, LEED AP for Homes Responds: Part I: Distribution

If not installed or maintained properly, forced-air heating and cooling systems can perform poorly, creating air quality problems and unnecessary expense. To optimize a forced-air system, you need to design or refine it to prevent leaks and pressure imbalances, protect it properly during construction (or make sure the ductwork is clean and sound), and use the right filter.

The performance spec of the heat (or cooling) source is also important, but it is critical to address the distribution system first before investing in better furnace and air handler performance. This article is the first of four focused on optimizing forced-air systems on the topics of Distribution, Filtration, Heat/Cooling Source, and Ventilation.

Leaks in the distribution system – the ductwork – can quickly undermine the efficiency of a forced air heating system. Ideally, the ductwork should be air tight and well-insulated. A “duct blaster” test, performed by a qualified technician, is the best way to find out how leaky the ducts are. In new construction, a “total leakage” test can be done at rough-in when all the ductwork is still accessible to measure tightness. If needed, theatrical smoke blown into the ducts can help identify leaks to facilitate sealing. If the ductwork is already hidden, a “leakage to exterior” test will identify how much heated air is leaking outside the building envelope. These are the most important leaks to fix since they represent wasted heat. A qualified home performance contractor (see resources below) can perform these tests, explain what the performance targets are for the home and how the system is actually performing. As a rough guide, the Northwest Energy Star target for new construction – a good benchmark for any home - is 6cfm@50 pascals per 100 sqft of conditioned floor area.

In an existing forced-air system, it can be very difficult and time consuming to access all the ductwork to fix leaks. In addition, old ductwork may be full of dust and other contaminants. These factors might lead you to consider replacing the whole duct system – an often overwhelming proposition with ducts buried in the building structure. There is an alternative: First, replace the accessible parts of the system, often located in unconditioned crawl or attic spaces, where in many homes up to 30% of the heat loss occurs. Second, strategically block and air-seal where ducts penetrate the building envelope and disappear out of sight, thereby ensuring they are enclosed in the building envelope. This can be confirmed with blower door and duct blaster to perform the “leakage to exterior” test mentioned above. (NOTE: If unlined building cavities are used as ducts, these must be lined or ducted)

If the thermal performance of the building envelope is significantly improved through weatherization and/or remodeling, this will affect the whole system.  Reduced heat loss/gain will result in smaller heating and cooling loads.  So a smaller furnace/heat-pump will keep the house comfortable.  Smaller volumes of air can be delivered efficiently through smaller ducts. We will discuss this further in the heating/cooling source article coming up (number 3 of this series).

A qualified technician or HVAC contractor should perform a “Room by Room” load calculation (ACCA Manual J or equivalent) and a duct system design calculation (ACCA Manual D or equivalent). This will show if your existing duct system is appropriately sized for your heating and/or cooling loads – and will inform the design/sizing of a new or replacement system.

You should also consider the path of air from the supply registers to the returns. Obstructions to free airflow along this path, such as closed bedroom doors, will cause pressurization of the bedrooms and depressurization of the core of the house where the return registers are located. These pressure imbalances can cause:

• Reduced supply air flow which may make the room uncomfortable;
• Increased leakage from supply ducts, wasting energy; and
• Most importantly, the risk of back drafting of naturally-ventilated gas- or oil-fired combustion appliances, as well as wood-burning stoves and fireplaces located in the core of the house. The negative pressure sucks flue gases into the living space instead of letting them exhaust to the outside—not a good situation. As a rule, combustion appliances installed inside conditioned space should be power-vented or, ideally, closed combustion.

Pressure imbalances can also cause poor-quality air to be drawn into the house from attics and crawl spaces or force warm, moisture-laden indoor air through leaks into wall cavities, where it may condense against the cooler surface exposed to the outside and cause serious moisture problems. You can mitigate small imbalances by installing return ducts in each bedroom, by installing transfer grills (a small duct often installed above a door connecting it to the next room or hallway) or jumper ducts (a duct that runs over the top of a partition wall, bypassing a bedroom door, for example), or by undercutting doors to allow some air to pass from room to room or to return ducts in each bedroom. A rule of thumb for sizing is one square inch of opening for each CFM of air supplied to the area “behind” the door.

During construction, don’t forget to protect the system from particulate pollutants by sealing supply and return registers and not storing ducts in the construction area before installation. Periodically inspect and clean registers and ducts if necessary.

Performance Testing Resources: To find a qualified Home Performance Testing contractor, check out websites for Building Performance Institute (BPI) or RESNET. If you are located in Washington see Home Performance Washington or Northwest Energy Star.

Alistair Jackson, LEED AP, CSBA is Principal in Charge of O’Brien & Company’s Residential Technical Services, and is a LEED for Homes Rater & Faculty, Energy Star Verifier and Performance Tester,  ARCSA Accredited Professional, and Built Green Verifier. Alistair was also a major contributor to the Northwest Green Home Primer where much of the information for this article originally appeared. It has been expanded upon for this publication.

Did you enjoy this article?  You might also like these Building Capacity Blog articles:
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 2
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 3
Tips for Optimizing Forced-Air Heating and Cooling Systems Part 4
Mechanical Systems and Fuel Choices for the Warming World
Creating Effective Energy Efficiency & Conservation Strategies Part 1
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