I know I owe everyone a redesign of our Performance Sticker and some talk of the various available home energy use metrics, but that is tall order, and I have been a bit short on time. So, instead I’m going to buy a little more time with a discussion of one of the lesser points that arose in the Sticker post comments . . . how involved does government get in the process of making performance stickers a requirement of the building industry?

Comparative energy use performance information has long been a staple of the auto industry. EPA estimates, for better or worse, have given us a means of comparing the fuel use of cars. They also give those of us obsessed with energy efficiency an open invitation to a dark pit of depression when watching car commercials. Seriously, they’re bragging about 24mpg? Pass me a pint of ice cream, a bottle of rye and my blanky . . . isn’t that how everyone deals with depression?

This testing is, as I understand it, carried out by the car manufacturers and reported to the EPA. The EPA then audits 15% or so of them to keep the manufacturers relatively honest. These tests are only performed on new cars and certain large models are exempt. For instance, GM is not required to provide Hummer data to the EPA. Presumably the 10mpg results would just be too embarrassing for everyone.

Car manufacturers test only a single representative of a given model for mileage as each is expected to be nearly identical. While the results are not always particularly accurate when compared with real life performance, they do provide a fairly reasonable means of comparing different models. For instance, I may not know what the exact, real-life mileage of my Accord will be, but I can be fairly certain it is going to be  15 to 20 mpg better than what I would get from that Dodge Ram.

All of this originated with a “Gas Guzzler” tax intended to encourage the production and purchase of more efficient private automobiles. Larger vehicles like trucks and vans were left out because they were seldom owned for private use. The law assumed if you had a truck or van, you had a legitimate use for it. How surprised those lawmakers would be today when a 6,000 lb truck is considered a perfectly reasonable vehicle for running your 80lb child to soccer practice.

Legally we can't call this a "Gas Guzzler"

So, how might this system apply to homes? Basically, we have a government mandated test for new products tied to a tax. Could that work in the housing market? With what changes? Believe it or not, I have an opinion.

Let’s start with the idea of a tax. We have an established habit of taxing things that have a negative effect on individuals and/or those around them. We tax liquor, tobacco, gas guzzlers, etc. We also tend to be more comfortable with taxes on non-necessities. At a NY grocery store there isn’t a tax on milk, but you’ll be paying one for the cookies to go with it. I think we can agree that low-performance homes fall in one if not both of these categories. So, a tax would not be outside  our historical inclination.

Let’s say we impose a graduated tax based on the projected energy use of new buildings. This tax would be levied either on new construction builders or buyers. I would argue builders as the buyers are going to be paying it either way. Leaving the exact metric out of this for the moment, let’s imagine that we base this tax on the results of some basic standard test and analysis. Results of this test must be sent to the appropriate agency. The agency would then levy the tax and provide an official document to be used in the sale or resale of the home in question.

There are, of course, some challenges. In this plan, each individual home would need to be analyzed. Solar orientation is the biggest reason for this individual attention, though variation in construction quality can certainly not be discounted. This could be conceived as an unreasonable burden on the builder. However, one could also argue that builders have been unreasonably unburdened in this respect for too long. Home performance, unlike performance in nearly every other consumer product, has remained relatively unchanged for a long, long time. This burden could also be reduced by providing a baseline rating based on code requirements. Homes would receive this rating without the necessity for more elaborate testing and be taxed accordingly. Builders would still be required to share the rating with potential buyers.

Another challenge could be oversight. If left to their own devices there is little doubt that some builders would be less than honest in reporting certain specifications. Insulation values, for instance, are an excellent opportunity for subterfuge. The oversight agency would have trouble auditing any of the reported homes for  those things, like insulation, which are difficult to inspect once a home is complete. This could be solved by third party inspection and oversight, but again we start to see the system become cumbersome.

A little drywall and this looks perfectly fine.

Lastly, energy use in a home is difficult to predict as so much relies on the habits of the homeowner. Any predicted usage is likely to be way off. However, this is a similar problem in our car example and rather than dissuade universal enforced use of some sort of metric, this unpredictability of behavior encourages it. The more universal the adoption of a metric like this, the more useful it is. This is because such metrics only provide truly useful information in comparison. Sure, the family that leaves the heat set to 85 and doesn’t believe in an off switch is going to use far more energy than the amount on their home’s  performance sticker. However, they can be reasonably sure that they would be using even more energy if they had bought the home with the lower performance rating.

So, to make a long post short, I propose a required analysis provided by a third party for all new homes. This would likely include a blower door test and a detailed analysis of all specs (orientation, insulation, mechanicals, etc.) including an inspection. In a perfect world, this test could be part of the municipal permitting process with the tax revenue from inefficient homes providing the necessary funding. The result would be an easy to understand comparative metric that would inform buyers and determine the gas guzzler style tax on the property. Of course, there is nothing perfect about this world, and my idea is, without a doubt, too simple to work.

To answer a valid concern in the comments of the original performance sticker post, I don’t think a program like this should be mandatory for older homes, but it doesn’t seem unreasonable to expect some required energy oversight for new or fully rehabbed houses. Older homes could choose to use the system as it becomes something buyers expect to see, but as was mentioned in the comments, there is certainly no need to waste money  to tell me a 100 year old Philly row home is inefficient. I expect it’s use in older homes to become a voluntary but eventually expected practice.

Well, I appear to have used this blog post to demonstrate something of the nature of inefficiency. My apologies. It is as Mark Twain once said, “I didn’t have time to write a short letter, so I wrote a long one instead.”

If you made it through, tell me what you think. Should we mandate the use of a particular metric to value the energy performance of new homes? Does an accompanying tax for poorly performing homes make sense? What other strategies are there for insuring consistent use of a single standard?

Use the comments to provide your own insights or to chastise me for my long, lazy and confusing writing.

We just settled on the Two Point Five Beta yesterday marking the completion of Postgreen’s eighth house. We don’t have final photography or LEED results yet, so this is just a quick celebratory post with a more comprehensive one to follow.

This house is the first to feature our new 1two5 Cabinets in the kitchen. The Sepviva Line, designed with matte laminates, aluminum edge banding and clean, simple lines was created for this house in Matte White and Terril. It features the Frigidaire slide in hybrid induction range and the Whirlpool/Bosch combo of fridge and dishwasher. The dishwasher blends in with a custom door panel. The final piece is a 2cm Ceaserstone countertop. We snapped some quick scouting pictures of this kitchen the other day with young Teague in the role of professional model. We felt his former work as an unhappy hipster qualified him for the work. Here’s a sample. More will follow when we take the actual professional shots.

In addition to the 1two5 kitchen the Two Point Five is home to another first. It is the first time we have beat the Passive House air sealing requirement of .6 ACH (Air Changes per Hour) at 50 Pa. Our final blower door came in at .54 ACH as you might have guessed from the cryptic title of this post. We will have more discussion of that in the coming week including how we got there and how it effects our final HERS rating.

Well, it’s a somewhat brief and unsatisfying post, but I promise more very soon. For now, feel free to put any appropriate unhappy hipster captions for the above picture in the comments. Check out the real site for inspiration.

We have talked about simple, mileage-style window stickers for homes before, but for some reason all that talk never led to action. We never actually created one for our own homes. Well, it’s time that oversight was addressed.

I put together a draft version of a window sticker based loosely on the specs from the recent Skinny Project. This is intended to be displayed in the windows of our homes as they are being built. Hopefully, combined with some of our other marketing tools, these signs will help teach people about the most basic differences between our homes and the rest of the market.

The sticker is based largely on the HERS (Home Energy Rating System) Index which provides a means of comparing relative home performance and offers an estimation of energy bills. The numbers presented are obviously just rough estimates subject to the actual behavior of the occupants, but I think they could have value in a comparative environment. Since these numbers are based on a third party standard, they should provide a useful reference when looking at performance across a variety of different homes.

I tried to keep the sticker relatively simple and display the most useful information as prominently as possible. Energy bills get prime placement with the HERS scale coming in second. I also used a bit of space to provide key specs related to performance. The bottom leaves a room for a disclaimer and logos for LEED and Energy Star. The numbers and specs above are just for demonstration purposes, but we hope to give this sticker an actual first run in the upcoming Avant Garage project.

So, what do you think? Could a sticker like this provide a useful resource to potential home buyers? Am I missing any key information? Is the effectiveness of this sign limited by the fact that no other homes will be sporting it?

Let’s talk it over in the comments.

We have started to explore larger projects with our development company in Philadelphia that include shared off-street parking lots with a common driveway. This provides a new opportunity to explore more sustainable pavement options than the traditional blacktop used in most projects. Part of our research, as always, is devoted to finding the best mix of sustainability and cost so that we, and others like us, can actually have a chance of implementing something new on a for-profit project.

First, a bit of quick background on how Philadelaphia’s Water Department is actually encouraging projects to use permeable pavement in larger projects. In Philly, the city requires projects that exceed 15,000 square feet of area to develop an approved Stormwater Management Plan. Typically this involves large underground detention basins and extensive piping. There is also a lengthy design process typically associated with the Philadelphia Water Department.

Fortunately, the PWD provides incentives to builders to fast track their design and approval process for stormwater management if they can satisfy the needs via “green” methods. This typically always includes some type of pervious paving surface where impermeable would typically be installed and a method of delaying roof runoff from entering the city sewers (think green roofs or giant rain barrels).  Yea Philly!

OK, now on to the different options available in pervious surfaces that you can drive a car or even a large truck over. We’ll cover the main types that we have run across and you can tell us what we’ve missed in the comments. All of these systems are installed in a similar fashion. There is often a bit more excavation and up to a foot of crushed stone or gravel installed prior to the paving surface in order to help facilitate collection and storage of large rainfalls without the surface experiencing flooding. Simple, smart and effective. Read on and enjoy my rating system.

Porous Asphalt (Blacktop)

That's a fancy stream of water!

Porous Asphalt, or Blacktop as the kids say, is one of the more popular options out there as it seems to be the most cost effective and widely accepted. After all, it looks pretty much like normal blacktop and asphalt is king for most of our roads and parking lots.

Cost – $
Maintenance – Lots
Porosity – ~176″/hour
Ability to Grow “Green Things” – 0 out of 5
Overall Sustainaearthgreenfriendliness – D+

The Asphalt starts out strong with low cost and effective porosity, but quickly loses points for requiring a lot of maintenance, zero ability to grow anything, being nasty and a strong contributor to the urban heat island effect. Don’t get us wrong, it’s much better than standard asphalt. We’d just prefer one of the other alternatives a bit more for smaller projects that don’t include thousands of miles of roadways.

The maintenance we are talking about is a biannual cleaning with a giant commercial vacuum type device to keep the voids in the blacktop from getting clogged over time. Sweeping or pressure washing won’t do and may only contribute further to premature clogging. Check out the National Asphalt Pavement Association for more info.

Pervious Concrete

Oooooooooh!

Pervious Concrete is the same concept as porous asphalt, except it’s concrete. It’s very easy to order and have installed by a skilled flatwork contractor, even if they have never used it before as it is basically normal concrete with no “fines” in it. This is how it remains open to water infiltration. A benefit over asphalt is that is will result in a much lighter color that will not contribute to the urban heat island effect as much. It is still concrete though and comes with the carbon footprint associated with concrete if you’re counting carbon points on your project. A bit costlier to have installed than porous asphalt, it is a choice we prefer if options are limited.

Cost – $$
Maintenance – Lots
Porosity – ~480″/hour
Ability to Grow “Green Things” – 0 out of 5
Overall Sustainaearthgreenfriendliness – C

One way to reduce your carbon footprint with any concrete order is to insist on local or even reclaimed aggregates and push for the highest amount of Fly Ash and/or Slag which are both reclaimed waste products. Pervious Concrete also requires the same biannual sucking that porous asphalt recommends. Check out PerviousPavement.org for more info on Pervious Concrete.

Pervious Block Pavers

Most commonly seen permeable concrete paver

There are many different types of Pervious Block Pavers popping up on the market now that the concept of saving the earth is gaining popularity again. The most commonly seen permeable paver is shown to the left and creates a hexagonal shape of concrete around a central pocket where grasses can be planted or simple gravel can be filled in.

Cost – $$$
Maintenance – Some
Porosity – Varies
Ability to Grow “Green Things” – 3 out of 5
Overall Sustainaearthgreenfriendliness – B+

That tire is really working up a sweat.

Since the popularity of this interlocking concrete paver had increase, more varieties have hit the market that look more like traditional pavers. An example is shown to the right. These pavers have less open area that is usually created either at the corners or by spacing the pavers on all sides to allow for infiltration. This type of paver can not grow anything in the voids, but is typically filled with gravel. It’s a nice option for those that want the traditional paver look with boosted functionality.

Tbe biggest deterrent to these types of pavers is the cost. Not only are the pavers themselves pricey, but the cost of install is typically much higher than the other varieties of permeable paving due to having to lay individual, small blocks by hand. There can be some maintenance with these pavers as they may individually settle or become misplaced after some use. They may also be damaged easier than a uniform pavement by snow removal in the winter. There are too many suppliers of these products for me to point to one source, but Google can help you out if interested in more info.

Drivable Grass

Drivable Grass with grass, sand, gravel & mulch filler

Drivable Grass is a specific product manufactured by the Soil Retention company. It’s kind of a unique product that we recently stumbled across at Greenbuild that I felt deserved it’s own category. The product melds a bit of the benefits of the other products into one system.

For starters, is comes in 2′ x 2′ mats that are much more affordable to have installed than the individual pavers. It also has a much larger exposed area (61%) for greater infiltration and more room to grow grass or ground cover in if desired. Also, unlike the traditional hexagon turf pavers, this system does not isolate the plant material into individual pockets. This allows the plantings to remain cooler and receive more uniform watering. These benefits result in a greener parking surface than most of the alternative plantable systems.

Cost – $$
Maintenance – Very Little
Porosity – I couldn’t find a spec. Sorry.
Ability to Grow “Green Things” – 4 out of 5
Overall Sustainaearthgreenfriendliness – A

Currently, this is our top choice to use in a few of the sites we are looking to develop in Philly that have shared parking areas. It looks like the cost will be less than permeable concrete and we will get the added benefit of creating a green space in the parking lot that requires much less maintenance than other systems which will reduce the HOA fees for the home owners. All good things so far.

Plastic Grid Systems

Yes, you can drive on these plastic cup things

Cost – $$
Maintenance – Very Little
Porosity – Lots
Ability to Grow “Green Things” – 5 out of 5
Overall Sustainaearthgreenfriendliness – A

Last but not least are the plastic grid varieties of permeable paving systems. Some of these get extra points for being made of recycled plastic and being fully recyclable themselves. We have done the least research on these systems, but the install seems straightforward and it can result in a fully sodded surface if desired. The main issue we saw was that it is recommended for light or occasional use parking lots if you want to maintain the grass on the site. If anyone has any experience with this type of product, please speak up in the comments.

Conclusion. That’s all I have. Contribute below.

We just got back from Greenbuild in Chicago and are a little more tired than expected. That is probably because we had to lug this sweet piece of hardware back with us . . .

That’s right, the 100k Project actually won the USGBC’s national award for LEED for Homes Project of the Year. We are very grateful for this recognition and hope to make it the first of many. We also hope to parlay this win into an actual speaking engagement at Greenbuild next year.

We are thankful (a fitting emotion this time of year) for everyone who worked on this project. We would particularly like to thank ISA for their architectural expertise and complete buy in to our crazy ideas and Magrann Associates for getting us through the LEED process and making sure we did what we needed to do for that Platinum rating. We also want to thank all of you out there following along, commenting, suggesting, critiquing, encouraging and just generally making us feel like this project was worth doing.

We will post more info on this award as it comes out, but for now, you can see the profile that was posted at Greenbuild in PDF form if you are interested. Thanks again and stay tuned. This is still just the beginning.

Over 1 million Energy Star Homes have been built to date in the US. Compare this to just over 6,500 LEED Certified homes and probably less than 20 Passive House Certified homes in the US. While Energy Star is much less stringent than the latter certifications, it is easy to see which standard the bigger production builders are turning to first in an effort to respond to the market’s demand for more environmentally friendly homes.

An Energy Star Home is basically trying to achieve 15% higher energy efficiency overall when compared to the same house built to code minimum standards. Our big two questions when forming Hybrid Construction were, “Is 15% efficiency improvement over code enough?” and “How many of the builders out there are just barely squeaking by with very minimal changes to the design of their old homes?”

There are some builders out there knocking the socks off of Energy Star standards, especially those participating in programs like the US Dept of Energy’s Building America and Builder’s Challenge programs (see chart above). This is swell, but for every builder that is far exceeding the minimum standards, there are probably 5-10 others that are doing the bare minimum to pass. We won’t name names, but we’ve heard a few stories of decent sized local builders completely missing the mark on large developments where Energy Star Certification had been advertised to consumers from the beginning. Insert embarrassing failure sounds here.

On to the point of this post. When we decided to launch our new construction company, Hybrid Construction, we realized that not everyone would have the need or desire to build to LEED or Passive House levels of construction. Therefore, we turned to Energy Star as a suitable target for our base level option in any Hybrid home that we are hired to build. When we sat down to think about it further, we realized that just hitting the minimum Energy Star goal would not be enough to satisfy the Hybrid brand’s base level of homes. Here are some of our main brainstorming points:

1. If we’re going to build an energy efficient home, let’s not stop at 15% better than code, but target 20% – 30% reductions.
2. If we’re guaranteeing Energy Star Certification, we need to target greater than 15% no matter what.
3. Energy Star is missing some key subjective elements that can not be ignored in Hybrid’s base homes. Things like type of windows and the use of really nasty materials like vinyl.

Below is a chart that we ultimately came up for the entry-level Hybrid 1.0 Energy Star house that includes items we felt any budget energy efficient home should be built to in the climate zone surrounding Philadelphia, PA. It is derived from the build levels chart on the Hybrid site, but focuses only on the base (1.0) level. For comparison, Hyrbid Construction just achieved efficiency levels 70%+ below code at it’s 3.0 build level. Below the chart is a bit more detail on the reasoning behind all of the choices.

Insulation Levels and Type

Insulation levels are a core factor in any Energy Efficient home and one that is relatively easy and affordable to increase beyond minimum standards when building a new home. Energy Star already recommends surpassing their minimums for new construction in their insulation chart targeting people performing retrofits to their homes. Why not follow suit and add a bit more in all new construction homes. It could cost as little as a couple hundred dollars extra in most new homes. If you’re filling your 2×6 wall cavities and 2×12 floor and roof cavities with decent quality insulation, you are there.

In the subjective category, we point out that dense-packed cellulose insulation is Hybrid’s preferred type of insulation. This will add some cost compared to standard fiberglass batts, but it is well worth it for a number of reasons. Fiberglass is not an option for Hybrid mainly due to it’s poor performance compared to cellulose and it’s high embodied energy. Customer satisfaction is very high with cellulose and it goes a long way in differentiating a house from all of the other traditional Energy Star homes out there.

Air Sealing & Windows & Ventilation

These categories are lumped together as we’ve learned in our research during Hybrid’s formation of what typical builders are doing. Most production homes in the US have inexpensive, vinyl double-hung windows. These are too leaky for Energy Star, so people are switching to single-hung which are a bit tighter. The single hung, however are still leaky enough that a builder can simply install an energy star bath fan and set it to run continuously to achieve the ventilation standards of the Energy Star guidelines. Stale air is sucked out and fresh air is simply brought in through the leaks in the windows and the rest of the house. That means that if it’s 20 degrees outside, that’s the temperature of the fresh air being transferred into your home 24/7.

Since poor air sealing can account for over 30% of a typical home’s energy costs (especially if insulated with fiberglass), we we felt that Hyrbid should take this pretty seriously in all levels of its builds. Most Energy Star homes get a $350 air sealing package from their insulation installer that basically includes spray foaming around key penetrations and stud to sheathing connections before installing the insulation spec’ed. Hybrid will do that also, but take it quite a bit further by adding the following:

• Taped exterior ZIP wall and roof sheathing
• Taped OSB subfloor
• Continuous sealant at critical rough framing junctions
• EPDM sill gaskets
• Gasketed interior to exterior penetrations (ie. plumbing stack)
• Foamed, caulked and taped Window & Door installations

Casement windows have much tighter air sealing components that do not loosen up over time when compared to double hung. They also have a more contemporary look while allowing more light and ventilation into the house. Now that the house is so tight, Hybrid will add a Heat Recovery Ventilator for about $500 that bolts directly onto the ductwork for the heating and cooling in the house so that unconditioned air is not being pulled directly into the house. A few minor and inexpensive improvements that have a big impact on the efficiency and quality of the house.

HVAC & Water Heating

We won’t go into a lot of detail here, but we want Hybrid to install components that are slightly higher in efficiency than the base Energy Star requirements without breaking the budget.

When it comes to hot water, using either an electric heat pump unit or a high efficiency gas tankless unit should blow away the Energy Star minimums for a few hundred extra dollars when compared to a minimum efficiency tank unit of the same fuel.

Heating and Air Conditioning is best done with a dual-fuel system in a typical home that has gas. A high-efficiency heat pump will handle the majority of the heating and cooling requirement, while a high efficiency gas furnace will supplement the heating demand on the coldest days of the year. Hopefully the increased efficiency of the home’s envelope will allow the budget to recoup some of the premium for the higher efficiency units by allowing a smaller unit to be spec’ed.

Appliances and Lighting

It’s hard to not buy Energy Star Appliances these days. We’ve found the key to going a bit farther than the competition is by spending a lot of time on the Energy Star site pouring through the appliance spreadsheets for refrigerators, dishwashers and clothes washers.  Often the smaller, no-frills appliances are much more energy efficient (and cheaper) than some of the more popular large appliances that may just not be needed by the end client. Notice it says “needed,” not “desired.”

Lighting for Energy Star is interesting in that you don’t need to install a single CFL to get Energy Star certified if you make up for it in your appliances. With lighting accounting for over 10% of a home’s energy usage (which will only go up as a home becomes more efficient) this is low hanging fruit. Put those CFL’s everywhere. The end home owner can replace any lights that may really annoy them or add their own lighting fixtures after they move in. By the way, CFL’s come in three color spectrums – soft white, bright white and daylight. Choose your favorite.

Subjective Issues Outside of Energy Star

Energy Star does not cover certain aspects, that we felt were important when forming Hyrbid, to any new home trying to position itself as both energy efficient and sustainable. The biggest glaring omission is water efficiency. It does not cost any more to add low flow bathroom fixtures and Water Sense toilets to a new house, yet it can have significant impact on the total water usage. By reducing water usage, specifically in the shower, you are also greatly decreasing the energy used to heat domestic hot water. Two birds, one stone…

Another category that adds no cost to a new home is using Low-VOC paints and finishes in place of toxic, off-gassing finishes that are used in typical homes. The homes will smell fresher and be healthier for your clients from day one, so there is no reason not to include this with any base Energy Star home. See the American Lung Association’s Health House certification for more on the benefits of healthier indoor air quality if you’d like to go to the next level and differentiate yourself further from other base Energy Star builders.

Last, but not least, we try to limit the use of toxic vinyl products in the home as much as possible. This means using fiberglass or aluminum clad wood windows over vinyl which also increase the home’s value. Another big one is vinyl siding, which is not only toxic, but hideously ugly and cheap in appearance. Try a durable fiber cement product that has a better appearance, includes a 50 year warranty and contains over 25% recycled content. Certainteed happens to make our favorite fiber cement siding that’s available in the US residential market at a very affordable price while also locally made.

Conclusion

Compared to the rest of the wealthy countries of the world, we have been building fairly lousy houses on average here in the US. The Energy Star program is a great tool to affordably improve the standard of new homes, but is it enough? Do you want to be another builder or home owner just scraping by minimal standards that most other countries would accuse of being way too lax in terms of energy and durability? Do you want to risk missing a new target because you’re aiming too close to the goal and only a few mistakes will cost you your reputation or a lawsuit? We all need to work together to deliver higher quality housing that beats standards like Energy Star by a healthy margin, while discontinuing the use of cheap and toxic building practices and products.

Do you have a different viewpoint? Don’t be shy. Share it with us in the comments.

The wait is finally over. The LEED for Homes Platinum Certification for both homes in the 100k project has been received. After a variety of delays including, most notoriously, the replacement of an incorrect bath exhaust fan, we have finally received official notice from the USGBC that both the 100k and (poorly named) 120k have acheived the highest status in the LEED for Homes rating scale.

We see this achievement as official proof that green building can be done for less. The 100k House reached this goal for less than $100 per square foot in hard construction costs and has proven itself to be a stylish, comfortable place to live (just ask Courtney). While we have slightly increased our construction budget for future homes, we see this success as a key foundation of our long term goals.

Did we make mistakes? Of course. Are there things we intend to do better/differently in the future? Naturally. But, we are still proud of our first project and would like to thank all of those who helped us make it a reality.

This milestone does not mark the end of the 100k project. We are currently gathering utility data and other long term project results that we will be sharing in the near future. We continue to learn from this project as we move forward with our construction efforts, and we will use the lessons to constantly improve our building methods.

We would like to extend a special thank you to MaGrann for guiding us through our first LEED for Homes process. The paperwork was occasionally painful and the process wasn’t exactly smooth, but they stuck with it and helped get these homes the recognition they deserve. Hopefully, our next LEED project (the Skinny Project) will progress more smoothly with equally impressive results.

Questions and congratulations will be heard in the comments.

As we build the Skinny Project, we are taking care with all of our air sealing details and making notes on possible changes to reduce labor and complexity in all future homes. One of the key notes I picked up at last year’s Passive House Conference was that those who had been actually building these homes for a number of years were all stressing multiple layers of defense against pesky air infiltration. I thought I’d throw out a quick post to give the basics of our current multi-layer approach at sealing the movement of that crafty air thing that is so prevalent on our planet from sucking the heat out of or into our homes:

1. ZIP System sheathing with all seams taped with butyl tape.
2. Combination of gaskets and sealant sealing all critical rough framing connections.
3. Dense Packed cellulose insulation.
4. Drywall gaskets or continuous sealant along all corners, top/bottom plates and window/door openings.
5. Locate outlets in the floors and use wireless light switches to eliminate all drywall penetrations in the walls.

More details and diagrams to come as we improve our construction docs for Awesome Town.

I’m not sure how we’ve forgotten to post on the Construction Waste Management done for LEED for Homes on the 100K House project? Let’s do a little recap here for all those interested. First we will briefly go over the LEED requirements and credits, and then we’ll take a look at the methods we used and the results.

LEED for Homes Waste Management Requirements

Prerequisites – Construction Waste Management Planning

1. Investigate and document local options for waste diversion from landfills including cardboard packaging and beverage containers the end up on the site.
2. Document the diversion rate for construction waste. Separate demo from new construction portions of a project if applicable.

Credits – Construction Waste Reduction

Reduce or divert waste from landfills to a level below the industry norm via either of the two options below:

1. Reduce construction waste – Generate 2.5 pounds (0.016 cubic yards) or less of net waste per square foot of conditioned floor area. See chart below for score.
2. Increase waste diversion – Divert 25% or more of the total materials taken off the construction site from landfills. See chart below for score.

100K House Construction Waste Management Results

We decided to go with the second method of verifying our diversion rate in order to gain our points in this section of LEED for Homes. It’s actually quite easy in Philly to do this thanks to a company conveniently named Construction Waste Management. All of the charts and pics that follow in this post are courtesy of CWM’s final report to us.

The beauty of this company and others like it across the country is that nothing changes on the site for the contractors. They deliver a standard dumpster to your site, you throw your trash it in like normal and they come take it away when it’s full. They then take the cans to an offsite location where they sort all of the material that can be recycled before sending off the remaining trash to the landfill. They even send you a lovely record of all of you dumpsters used per project which is exactly what the LEED folks are looking for in terms of verification for these points.

Here is our summary chart from Construction Waste Management:

This chart represents the aggregate total from three cans we used on the 100K House project. Since we diverted over 75% of our waste from landfils, we earned 2.5 points for this section in LEED. That’s just half a point from the maximum 3.0 points that can be earned for diverting over 88% of your waste. Not bad and I think a full point higher than we accounted for in our initial LEED checklist.

Construction Waste Management Images

To finish up this post, we thought you guys and gals might enjoy a more detailed look into the Construction Waste Management company’s operations. There are many similar companies sprouting up all over the country and their rates are often lower than traditional waste companies as they have an extra stream of income from selling the recycled materials they claim from construction sites. So it’s greener and cheaper! That looks nice in print.

Example of a dumpster being emptied for sorting offsite at CWM

Wood is sorted and made into mulch


Plastic is baled and sent to a recycling center


Steel is stockpiled and then shredded


Cardboard is recovered, baled and sent off to be recycled


Drywall scraps are pulverized

We thought it would be a good idea to review our new ventilation strategy and design implemented in the recent Passive Project. The ventilation strategy in the 100K House was different than most typical houses and the Passive Project took things a step further. We’ll start with the outline:

1. Use a very efficient mechanical ventilation system (ERV or HRV >90% efficient)
2. Design an efficient duct run layout to maximize efficiency of your ventilation system
3. Eliminate all dedicated local exhaust systems ducted directly outside
4. Eliminate all dedicated appliance exhausts that are ducted directly outside

High Efficiency Mechanical Ventilation (ERV or HRV)

The Passive House standard requires that you install a ventilation system with > 75% efficiency and a low electric consumption of 0.45 Wh/m3. When we say ventilation system, we are talking about either a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV). HRV’s exchange heat only while ERV’s exchange both heat and humidity.

A 75% efficient unit will be exchanging 75% of the heat from the indoor air with the cold air coming inside. The closer that figure is to 100%, the closer the fresh, incoming air will be to the existing indoor temperature. Efficient electrical consumption is basically referring to the type of motor used in the ventilator. European models typically are using the most efficient DC motors available, while unit made in the US will suck a bit more power.

If you are shopping the globe, you have a couple of options for mechanical ventilation that meet the Passive House reqs. If you want to buy in the US, you have one choice – The UltimateAir RecoupAerator.  This bad boy comes in black, runs at 95% efficiency and sucks a paltry 40 Watts while delivering 70 cfm to your home (250W @ 200cfm). This is what we spec’ed on 100K and continue to use in Passive and for all foreseeable projects in the future. We set it on its lowest setting which usually measures about 60cfm in each room vent and let it run 24/7/365. Simple.

This unit also comes standard with a MERV 12 filter which gains us LEED points and keeps our client’s air very clean. Lastly, it features an “EconoCool” feature that can be used during the summer to reduce cooling loads. Flick this switch on and the unit will recognize when the temp drops below 65 degrees F and automatically shut off the energy recovery and begin swooshing that cool night air directly into your bedroom.

Maximize Efficiency with a Well Designed Duct Layout

Now that we’ve got the correct ERV for our needs, we need to pay attention to how we run our ductwork to maximize efficiency. The ERV will suck out stale air from the home and deliver fresh air to rooms at the same time. Below is how our PHIUS consultants recommended that we locate our suckers and blowers (technical Postgreen terms):

Stale Air Exhausts (Suckers)

• Bathrooms
• Kitchen
• Near Washer/Dryer

Fresh Air Inlets (Blowers)

• Bedrooms
• Living Room

Now we don’t just want to throw the ductwork in any old pattern to get to these rooms. We want to minimize 90′s and have straight runs as much as possible. Basically a 90 degree turn is equivalent in resistance to airflow as 25′ of straight duct and a 90 degree register termination can add as much as 80′ to your calcs. The main pointers given by both PHIUS and the manufacturer of the UltimatAir are as follows:

1. Keep it SHORT
2. Keep it STRAIGHT
3. Keep it SMOOTH
4. Test after the system is commissioned

The diagram above is a 3D layout of our proposed duct runs for the Skinny Project. Laying these out in Sketchup is pretty quick and helps us really think about how each duct run needs to get to it’s final destination with the fewest turns. As a result of this exercise we added another small chase wall next to one of the closets in an upstairs bedroom. This chase will not be seen, and could be considered a minor detail, but it will greatly improve our duct efficiency and reduce labor time for our installers.

Other tips given to us for optimal ERV system performance:

1. Always use smooth, hard duct and avoid flexible duct as much as possible.
2. Insulate the two lengths of duct running between the exterior and the ERV. This will prevent condensation from forming on these lengths of ducts.
3. If noise is a concern, add one 3′ section of insulated flex duct to the supply side of the ERV. Install this section as straight as possible and it will act as a silencer without needed to buy an expensive silencing duct section.

Eliminate Dedicated Local Exhaust

The big difference between the 100K and Passive ventilation strategies was increasing the amount of intakes/exhausts inside and eliminating the local exhausts in the bathroom and kitchen. PHIUS highly recommends doing away with any local exhaust that is basically sucking conditioned air directly out of the homes and replacing it with whatever outdoor air can be sucked through any cracks in your envelope. Eliminating the local exhausts also reduces your exterior penetrations through the envelope by at least two (more if you have more than one bathroom).

To compensate for the lack of dedicated local exhausts, we install suckers in the bathrooms and kitchen. On top of that, we throw an ERV boost switch in each of these rooms so that occupants can boost the ERV fan to max setting (around 200 cfm for UltimateAir) while they are in use. These switches are also useful for parties or times when a lot of CO2 producing bodies are inhabiting your space.

In the future we plan to take this boost switch a step further by linking it directly to the bath lights with an auto shutoff delay. Basically when you turn on your bath light, the ERV will automatically boost to high. When you leave the bath and turn off the light, the ERV will remain on boost for another 10-20 minutes to fully clear out any fumes you may have generated during your visit. This gets us a LEED point also.

Eliminate Exhausts for All Appliances

This is less of a ventilation system design aspect and more of a whole house envelope and mechanical design strategy, but I like to include it here as well for good measure. By using electric water heating backup for our solar thermal and a condensing dryer that does not require venting, we have eliminated all appliance ducting to the outside. Less thermal bridging and warm air being sucked out of our homes. To compensate, we locate a sucker near the condensing dryer that can tend to get a little steamy at times. In the future designs, the washer/dryer is moved into the bathroom to allow the bath sucker to serve two functions.

That’s it. I hope this helps with any mechanical designs you may be considering for your next green building project. Comments are below.

One last note:
One question we still get a lot is if our homes are too tight and cause indoor air quality problems or pressure balance issues that would cause the windows and doors difficulty in opening and closing. This is a bit of an outdated concern from when production builders first started making their homes tighter without adding mechanical ventilation. Now, this issue is a thing of the past unless you have a very poor builder…