LEED for Homes Overview

With all of my experience in LEED, I was under-prepared for the differences in LEED Homes.  I have a better appreciation now for the nuances of the Homes system, and thought I would share with you an overview of LEED Homes, and some of the lessons learned on this project.

LEED for Homes is comprised of eight sections: Innovation in Design Process, Location and Linkages, Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, and Awareness and Education.  I will briefly describe each of the sections and their intent.  Each section is comprised of design and construction best practices.  Completing the intent and requirements of each of these best practices will help accumulate points in the rating system.  Some best practices are prerequisites that must be completed in order to achieve the rating. 

The Innovation in Design Process in LEED for Homes has several goals. The first is to encourage integrated planning before construction.  This is not a well accepted principle in commercial design, and even less so in residential design.  Integrated design offers opportunities for synergies that can reduce first costs in construction.  The second goal is to plan for durability.  In this process, we identify potential risks to the structure, like moisture, pests, and weather to name a few, and then incorporate protections into the design of the structure.  Finally, the process encourages both excellence in the execution of the project, and thinking of environmental design and construction best practices that have not already been developed. 

The Location and Linkages section relates to the carbon impact of the location of the site.  LEED provides greater incentives for projects located in more urban areas.  This is because the carbon footprint associated with reduced transportation, utility distribution, and access to services has a global impact.  Residents of downtown Chicago can exist happily without owning an auto as all services are within walking distance or near public transportation.  The more remote the location, the more dependent an individual is on a vehicle to gain access to the services they require.   

The Sustainable Sites section deals with how we minimize the impact of our building footprint on the land.  Ideally we try to make the building invisible to the land as if the land existed in pre-European settlement.  How does rain percolate into the ground?  What flora and fauna would we encourage?  How does the color of the building material affect the temperature of the land?  What chemical inputs are can we eliminate? 

Water Efficiency deals with water use both in the building and on the site for irrigation.  We can reduce water use with more efficient plumbing fixtures, and we can even harvest rainwater to use in the flush fixtures and for irrigation.  We can also plant native plants that require very little to no water and avoid any irrigation.  Native plants have had millions of years to figure out how to survive on natural rainfall, and there is no need to supplement their growth with irrigation or chemicals. 

The Energy and Atmosphere section deals with the energy efficiency of the energy consuming devices in the home.  The primary goal is to reduce the demand for energy by developing an energy efficient building envelope, and then installing the most energy efficient energy consuming devices possible.  High efficiency heating, cooling, lighting, and appliances all contribute to minimizing the energy load.  Once the energy load has been minimized, you can begin to add energy production into the mix.  Solar, wind, geothermal, and biomass burners are some of the alternative energy sources that can be integrated.  We selected solar power for this project as we had determined that we did not want to use any fossil fuels as a design ethic, and it seems the most elegant ultimate solution as solar power is the source of all other forms of energy.  Wind power was not a possibility on our site as we are located in a depression and surrounded by tall trees.

The Materials and Resources section encourages us to use materials that have some environmental performance characteristic.  This can be locally sourced, contain recycled content, contain a rapidly renewable material, or have a low VOC content.  LEED Homes recognizes achievement of any one of these sustainability criterion. 

Indoor Environmental Quality is to me the most important of all of the sections.  This affects our health directly by integrating all of the design elements that affect how we interact with our interior environment.  Air quality is of paramount importance.  Since the 1970’s when we began to construct tighter buildings, the term “sick building syndrome” began to enter the lexicon.  We now know that that was the result of the many chemicals that were introduced by building products, furniture, poor design, and poor construction practices.  Dealing with moisture, contaminants, and proper ventilation, by design to compensate for other factors contributes to better health.  Immune disorders, respiratory illnesses, and allergies can be improved by controlling the design and construction of a building.  

Awareness and Education is designed to educate the homeowner about how to use the technology that has been designed into the home, and also to promote green building in the community as an educational outreach.  As the designer and contractor of my own home, I am familiar with every aspect of the building.  I assembled the Operations and Maintenance Manual which is three 3” thick volumes of documents describing every aspect of the building.  I had my mechanical contractor perform a video documentary of the maintenance of the HVAC system, so I have no excuse for not knowing how to operate it.

I often call LEED for Homes the red-headed stepchild of the USGBC.  All of the other rating systems operate in the commercial construction sector.   Having worked in both residential and commercial construction, I can state that the construction vocabulary, skill sets, professionalism, and the capacity to deliver a product are different between the two sectors.  The LEED Homes rating system wisely accommodates these marketplace differences.  There are many aspects of LEED Homes that are justifiably unique to this rating system.  The rating system is simplified by reducing the amount of documentation required, and is facilitated by a team of experts to assist in the process. 

Though I applied the experience I gained through my knowledge of LEED in the commercial sector, I have come to appreciate the LEED for Homes rating system and the capacity it brings to the residential sector to bring about marketplace reforms.  I think the next generation of the rating system will enhance the LEED for Homes brand, and improve the mission of establishing environmental standards for residential design and construction practices.

Lessons Learned

I thought I would share my experience with the Passive House (PH) design system, and relate how it works with LEED.  I had been enamored with PH for some time as a rigorous energy design system.  Having many years of experience in construction and being reasonably computer savvy, I ordered the PH software about six months before I began construction, thinking I could work through the logic and design my own home. 

I gave up after six months of trying to deconstruct the logic and hired John Semmelhack of Think Little.  As it turned out, John is the chair of the Technical Development committee for Passive House US (PHIUS).  He is familiar with a number of the different energy modeling software applications, and was able to complete the modeling on our home in about one day.  With his facility in performing the calculations, I have no reason to attempt to learn the software as I can rely on his expertise.

Though John was able to get our design to comply with the PH requirements of less than 0.6 Air Changes per Hour (ACH), and 4.75 kBTU/(ft²yr), the cost of achieving that exceeded our budget.  The primary driver of that cost was the building geometry.  Since a primary objective was to build a barrier free home, we designed it all to be on one level.  This meant that the ratio of exterior wall and roof area to the floor area was not optimal for thermal design.  It was more important to us to have the barrier free design that to meet the PH requirements, though we came very close.  We exceeded the air infiltration requirements by getting down to 0.44 ACH, but only got down to 7.20 kBTU/(ft²yr).  The only changes we made from the original PH design was to reduce the thickness of the perimeter walls from 22” to 19”, and specify a window that was not quite as high performing as the one that would attain the PH rating. 

The savings allowed us to purchase a ground source heat pump which performs both heating and cooling for us.  Due to the efficiency of the thermal envelope, the heat pump we purchased was the smallest one made, and we are only using half of that capacity.  If the next owner chooses to finish the attic, the heat pump will be more than adequate to the task.  As we get older, our thermal comfort will become more and more important, and having this thermal control will be a benefit.  I also work out of our home, and my productivity is tied to my thermal comfort.  The PH design did not include any cooling, so this was ultimately a good choice for us for the long term. 

There is some tension between the advocates of Passive House and LEED, though there need not be.  Passive house is strictly a building energy model that deals with the energy efficiency of the home.  It operates beautifully within the Energy and Atmosphere section of LEED to maximize energy efficiency.  However it does not deal with any of the other environmental best practices described by LEED.  LEED is more holistic as an environmental standard, considering other tangential energy inputs such as the energy costs of commuting to the site and material delivery.  However LEED does not mandate the strict energy requirements of Passive House. 

My goal in implementing Passive House standards was to develop a return on investment that would pay for all of the energy costs of the building for the lifetime of the building (which I hope to be 100 to 200 years) within the first 5 to 10 years.  We implemented the most energy efficient envelope, appliances, and alternative energy sources we could afford in a coordinated effort to achieve that goal.  Time will tell what the actual return will be. 

Things we would do differently:

The dual stud wall was designed to eliminate thermal bridging.  With the 4” of rigid insulation on the outside, we do not have any thermal bridging, so we had some added labor for the wall construction.  Constructing the walls out of 2x10 material would have simplified the erection process, but the materials would have cost about $500 more. 

I would have been more adamant about the concrete sealer.  Due to poor communication on my part, the material we have is like a hard shellac.  It scratches easily, and in the space of a couple of years is going to look terrible.  At 9:00 every night our two cats start chasing each other around the house.  When they try to get traction on the smooth floors they look like Willey E. Coyote spinning his legs and they leave scratch marks on the finish as they skid to a stop.  What I had wanted was a concrete hardener which would have served roughly the same purpose, but not have been as shiny.  This would look like the concrete floors you see in most of the large box retailers like Home Depot.  We could apply a wax to it to prevent staining and would produce the same polished finish.

I wish we had thought of the cedar shake shingle as a siding material earlier.  We committed a lot in labor and material cost for the installation of the plaster lath.  The cedar looks much better than the stucco would have, and the whole house sits much better on the site for the change in materials.  In hindsight, the stucco would have been a boring finish. 

Things we love: 

We love the clear span concrete in the basement.  Not having a beam and columns in the basement provides a lot of options for use.  We had designed the basement for use as a storm shelter, storage, and mechanical room, but it is going to take on a more prominent role at some future date. 

We love the concrete floors.  The finish notwithstanding, cleaning the floors is a breeze.  About five minutes with a dust mop cleans the whole house, then a little bit of damp mopping here and there periodically as needed.  We do have some area rugs for color, comfort, and acoustics in a few areas, and we need to drag out the vacuum for those, but it only takes about another five minutes to finish the vacuuming.

We love the Serious windows.  These are extruded fiberglass windows, and have a somewhat commercial storefront design to them.  They perfectly frame the views we had hoped to capture, and the thermal comfort is superb.  We have tested the temperature at the window ledge at one degree of difference from the center of the home when the outside temperature was 50^o F lower. 

We love not having any drafts.  After living in homes that were over 100 years old for the last 30 years, we have had no complaints about drafty conditions.  Even though there is a lot of glass, the thermal efficiency of the window does not even generate any noticeable convection to cause any discomfort.

We love the radiant floor heating and cooling.  Warm toes make a great difference in thermal comfort, and we really enjoy the even heat that is distributed throughout the house without the air currents of a forced air system.  The same goes for the cooling.  This summer was especially hot, and we could feel the coolness radiate from the floor.  After working outside installing the siding this summer it was a welcome relief to come in and recover on the cool floors.

We love the Energy Recovery Ventilator.  We had some issues with the installation.  We had some testing done to see if it was delivering the proper amount of air, and found that it was short about 30%.  When the power failed once during the summer, we felt as if we were suffocating within about 8 hours from lack of oxygen.  We had installed flexible ductwork in the basement to the ERV, which is not as efficient as metal ductwork.  When we changed it to the metal ductwork, we were able to operate the fan speed on the low setting and feel just as comfortable as we felt previously when it was operating on the high setting. 

We love our yard.  We opted not to have a lawn and enjoy nature right up to the edge of the house.  We installed a six foot gravel rainwater collector around the perimeter of the home to hold back the vegetation, and planted a no mow native plant species for the first 20’, then planted prairie grasses over the rest of the disturbed areas of the site.  Some of the grasses are designed to attract wildlife, and one is designed to be shallow rooted wildflowers for over the drainfield.  Though we have not experienced a full year of growth, and it takes about three years for a prairie to mature, we are really looking forward to seeing this develop.

The rainwater harvesting system is something I wanted to do to test the economic efficiency of the technology.  I knew the economics would be marginal for our use as we only intended to irrigate the garden.  I did however really want to eliminate the need to clean out gutters on this tree lined site as we get older, and this presented itself as a solution.  We normally get 36” of rainfall in this region which is more than enough for any native plant life.  This year we experienced a drought that lasted nearly 8 weeks, and our cistern ran dry.  The next 8 weeks we had rainfall every few days and required no irrigation.  The right mix of capacity and need seems to be a function of rolling the dice. 

Done…ish

The solar panels are finally operational.  The power company finally recovered enough from assisting the clean up efforts after Hurricane Sandy, and came to install the new meters.  The existing meter needed to be removed, and a new dual meter box installed.  The meter box required a new feed from the solar panels, and then new meters were installed.  This all occurred over the space of a day.  We were without power for about four hours while the wiring was done. 

 

The panels were powered up at noon on Monday, and produced 2,000 watts (2kW) of electricity under a hazy sky.  On Tuesday the sky was heavily overcast, and the day’s production was 3kW.  This is what is recorded on the supply side meter.  I do not yet know if this is the net consumption for the home, or if it is just the raw number for production.  I should know when I get my next utility bill. The two electric meters, phone interface, and generator interface are shown in the picture below.

Nights have been getting down into the low to mid 20’s (F), and days have been in the upper 40’s.  On sunny days we have been getting at least a 4 to 5 degree boost in temperature from the sun warming the slabs on the south side.  One modification I would like to make to the mechanical system is to be able to circulate the water in the radiant floor heating system when the sun is out to re-distribute the heat from the south side throughout the house.  This should be easily done with the small 1/10^th hp pump which is already in the loop and a thermostat that samples the temperature on the south side. 

That completes that last major project on the house that makes us fully operational.  Now we have a number of smaller initiatives that we will implement over the next year or two to finish up.  These are more in the nature of a honey-do list than construction. 

A relatively significant project on the wish list is a monitoring system that would provide data tracking for the major energy using devices that we can web host.  We already have some limited ability with our HVAC equipment to do data tracking, but this does not provide a comprehensive look at energy consumption.

 

Last week we had our Green Rater Michael Holcomb of Home Inspector General do his final review of our project.  We went through the checklist and tentatively came up with 105 points on the LEED Homes rating scale.  We needed 88 points to reach the highest rating of Platinum.  The new version of LEED Homes (V4) that has just been released in pilot form has raised the bar significantly, and we plan to see how well we perform in the new rating system.  Our expectation is that we will just barely achieve the Platinum level designation.  All of this is subject to the final review by USGBC National.