LEED BD+C: Homes v3 - LEED 2008
The Vandemusser Residence
LEED Platinum 2011
* This profile has been peer-reviewed by a USGBC-selected team of technical experts.
The below stakeholder perspectives address the following LEED credits:
IDc3.1, MRc3.2, EAc1.2, SSc2.5, WEc1.1, MRc2.2
Goals and motivations
What were the top overarching goals and objectives?
The first and primary goal on the project was to ensure that the home would be net-zero. When construction started, it was unknown whether the active solar components would be integrated in the original construction phase or whether it would merely be roughed-in for future integration . It's the primary reason why we focus on designing every home to be "net-zero ready". Money is almost always the limiting factor when constructing a new home, but it shouldn't preclude someone from improving the energy efficiency of their home down the road when additional funding becomes available. Ultimately, the State, Federal, and utility incentives that were available at the time allowed us to move forward with the installation of both the solar thermal and photovoltaic panels during construction of this home.
Secondly, the home also functions as our professional office. As a result, we implemented more technologies than we would typically design for a client so we could use the home as a showroom. We also focused on integrating certain technologies (such as radiant heating, solar panels, and LED Lighting) as seamlessly as possible to show that with careful design integration, a net zero home can blend into the neighborhood. Conversely, we made certain technologies more prominent so that clients could really see how they function. For example, the 3000-gallon storage tank sits proudly up against the rear wall of the house and affords us the opportunity to demonstrate efficient residential water usage.
View from living room through dining room to kitchen floor-to-ceiling passive solar windows on the left side, FSC-certified cherry kitchen cabinets in the kitchen, polished concrete floors provide excellent thermal mass for the passive solar heating, engineered rafters utilize recycled waste wood, all CFL and LED lighting throughout.
Thirdly, we maximized the financial incentives available to us via local, state, and federal programs to show that these technologies don't have to be expensive when the home is properly designed. Local incentives included builder permit fee and utility rebates, state incentives included passive solar and other renewable energy tax credits, and Federal incentives included builder tax rebates and renewable energy tax credits.
What were the motivations to pursue LEED certification and how did they influence the project?
- Cost/Utility Savings
- Design Innovation
- Integrated Design Process
- Vehicle Miles Travelled (VMT) Reduction
- Waste Reduction/Avoidance
Based on the stated goals of us as clients and our primary work as energy efficiency consultants, it was a no-brainer to have the home certified for LEED for Homes. Each of the motivations that were identified could easily be boiled down to the cost and quality of life benefits that resulted.
The monthly savings we experience when compared to an equivalent built-to-code house is an easy cost benefit to identify. By integrating these technologies into the home design at an early stage, we made it easier for the builder, simplified the layout of said technologies for me as the architect and my wife as the engineer, and reduced overall costs as a result.
Our home design was informed by the local, state, and federal incentives that were available. Doing this maximized the savings that we gained through each of the technologies. For example, the solar thermal water heating system has an estimated payback of less than 2 years due to the various incentives available. By designing the south window glazing percentage to meet the state passive solar tax credit requirements, we were able to write off not only the cost of our south-facing windows, but also the thermal mass of the home and the window shading strategies implemented. Two-thirds of the cost of our geothermal heat pump was given back to us in the form of state and federal tax incentives. It's amazing how much money is available for energy efficiency improvements when you know what to look for!
Because we now work out of our home in our lower level office, we have reduced our drive times considerably. Our employees all live locally and also experience extremely short drive times. Because of the passive solar orientation, the office is bright and cheerful, which results in increased productivity and very good morale. I can't imagine ever wanting to move our offices again.
Because so many of the components of our house were prefabricated (such as the structural insulated panels and prefab foundation walls), there was very little waste over the course of the construction. The builder was amazed at how few dumpsters were necessary to take debris away.
What were the most notable strategies used to earn LEED credits?
Probably the biggest effort was put toward reducing the HERS Index of the home - namely, how much more efficient we could be when compared to a built-to-code version of our house. This impacts the number of points awarded under section EA 1.2. We wanted to see how far we could get using conventional building practices.
View looking from kitchen through the dining room into the living room. Note passive solar windows on the right and upper balcony to access operable windows for natural ventilation.
Even without the active solar component that was added on at the end of the project, we were able to get the HERS Index down to 44, which equates to 56% more efficient than code. That's from building a tight, well-insulated envelope and orienting and designing the house to effectively use the sun's energy. Once the active solar was incorporated at the end of construction, we were able to get the HERS Index down to 16, and efficient use of utilities got us the rest of the way to net-zero.
We also did quite well under the Water Efficiency and Irrigation reduction sections. Due to the large amount of rainwater collected off the roof, and its use toward flushing of toilets and outside irrigation, we effectively cut our water usage by 75%.
By careful selection and use of materials, we also were able to take the maximum number of points under Environmentally Preferable Products MR2.2. This was through the use of a combination of locally manufactured, low-VOC, and recycled materials. The basement and main floors are polished concrete slabs, which utilize a zero-VOC sealer, are extremely durable, and provide excellent thermal mass for passive solar heating throughout the home. All paint is zero-VOC Olympic Premium, and all wood trim is sealed using low-VOC, water-based Minwax Spar varnish. The wood floors in the upper level of the home are FSC-certified Eco-Timber pre-finished engineered poplar planks. The flooring in the kitchen and yoga room are renewable cork tile flooring. Because of the lengthy rafter spans required for much of the home, the use of engineered beams (Parallam) was necessary to support the structural insulated panel (SIP) roof. The beautiful pattern created by the lamination was left exposed as part of the final finish and worked so well that the same Parallam material was used for interior railings and stair treads. All kitchen and bath cabinetry was provided by Smart Cabinetry and was built with FSC-certified cherry and zero-VOC finishes.
What cutting-edge strategies or processes were implemented?
The biggest uncertainty for us on the project was how well the rainwater catchment system was going to work. The goal was to create a catchment system that was inexpensive, simple to maintain, and provided good quality water for the purpose of flushing toilets and outside irrigation. Limiting the water usage to those two items allowed us to use a simple non-potable storage system. The gutters on the rear of the house run to an above-grade storage tank with an exposed basket filter. The black, plastic tank has full south exposure which helps to keep the water from freezing in the Winter. The opaqueness of the black plastic also inhibits algae growth since sunlight access is essentially eliminated inside the tank. Instead of a submersible pump in the tank, the pump was brought into the adjacent mechanical room which simplifies maintenance and access. The plumbing to the toilets and exterior hose bibbs was plumbed separately from the rest of the plumbing in the house. Through a series of solenoid and backflow preventer valves, we have the ability to switch the rainwater systems over to city water in the unlikely event that the tank ever runs dry or if the power goes out.
Photo taken from the Southeast corner of the building site looking toward the rear of the home. Note the 3000-gallon rainwater cistern in the background.
I'm happy to report that it has probably been one of the biggest successes on the project. Everything works exactly as designed! Even though water is inexpensive where we are, we have numerous clients who do not have access to city water where effective use of rainwater could potentially save them thousands of dollars in well-drilling. Our ability to show them how our system works has allowed us to convince these clients that there are definitely outside-the-box solutions to water access problems.
How was the integrative process applied and what was the greatest benefit gained?
The greatest benefit we experienced in the integrative design process was with the solar installer, First Light Solar. As design professionals and homeowners, we had a general knowledge of solar technologies. However, it wasn't until the solar installer came out and discussed options for both the photovoltaic and solar thermal systems that we really came to understand how critical the system selection and location on the roof would be. By discussing this early in the design process, it became much easier to integrate chases (a framed enclosed space around a flue pipe or a channel in a wall, or through a ceiling for something to lie in or pass through) and locate spaces to hide equipment. This early discussion also helped us to decide that it made sense to do the active solar portion of the work now rather than later due to the then-current prices of panels and deadlines for various incentives and rebates. The decision to install these systems then likely saved us several thousand dollars.
Aside from LEED certification, what do you consider key project successes?
Ultimately, I am reminded of the success of the project every time a client comes in and says, "Wow. I could definitely live here!". It drives home the point that being net-zero doesn't have to be expensive or look out of place. It brings a smile to my face whenever someone asks (in the middle of winter, no less) if the HVAC system has been running all day and I can confidently tell them that the HVAC hasn't run at all - they are feeling the thermal mass floors radiating the sun's energy back into the room.
View into living room. floor-to-ceiling passive solar windows on the right side, polished concrete floors provide excellent thermal mass for the passive solar heating, engineered rafters utilize recycled waste wood, all CFL and LED lighting throughout, LED TV uses less than half the energy of an equivalent-sized plasma TV, EPA-certified, high-efficiency, wood-burning fireplace insert.
I also consider our ability to get to net-zero as a major success on the project. It wasn't easy - in addition to creating a tight, well-insulated thermal envelope, incorporating efficient HVAC and water heating strategies, and the active solar components, we really had to look at the electrical usage of the house by circuit to see where we were wasting power. With simple modifications to when we used certain appliances and turned equipment off, it was the last piece of the puzzle to become net-zero.
View from master bedroom looking toward South windows.
What were the most important long- and short-term value-add strategies and what returns on investment (ROI) have been experienced or anticipated?
Some design decisions were made regardless of the return on investment (ROI), since we wanted to have the ability to show examples of certain technologies to clients. While we knew that some of these decisions would not necessarily pay back quickly, it was still interesting to see how we felt about them once we had moved in and had time to think about their effect on our use of the house.
In terms of long-term value, it's hard to express how important it is to have access to natural light. The additional benefit to a passive solar home, beyond reduction of energy usage, is the quality of light gained. We rarely use lights in our house by day, even on cloudy days. The quality of sleep has been drastically improved when compared to previous homes. We wake up with the sunrise instead of an alarm clock and find ourselves to have more energy throughout the day.
In terms of return on investment, the quickest payback we have seen in the house has been with our solar thermal water heating system, which supplies the majority of our domestic hot water. State and Federal incentives reduced the cost of the system by 65%, and the local utility had a $1000 incentive in place at the time of its installation if we allowed them access to our utility bill data. The solar thermal system will have paid for itself in 1.5 years.
What project challenges became important lessons learned?
The most valuable thing we did during the course of the project was to keep the lines of communication open between us as the designers / homeowners, the general contractor, and the subcontractors on the project. Everyone understood that their opinion was valued and if a better, less expensive, or easier option came to someone's mind for a particular aspect of the project, they were encouraged to share with the project team. This often came into play during construction and resulted in creative solutions to what could have been awkward or mundane aspects of the house.
Significantly, we have needed to use very little heating and cooling via HVAC. We were surprised at just how much of our thermal comfort is addressed by simply taking advantage of the passive solar aspect of the house. The sun does the majority of the heating, even in the coldest winter months. Conversely, the window overhangs do an amazingly effective job of keeping the house cool in the middle of summer. For that reason, it often makes sense to recommend that if the thermal envelope and passive solar orientation is sufficient, it may not pay back to install the most cutting-edge, highest efficiency HVAC system on the market if there are no financial incentives. This is also true regarding radiant floor heating systems. As much as we love our radiant floor heating on those coldest days, the truth is that it doesn't run all that much. The sun does the majority of our radiant floor heat throughout the day. The radiant floor heating was definitely one of the most costly items we might have eliminated in hindsight, especially considering the difficulty of coordination and infrequency of use. It is definitely something we try and discuss with people when they come to us with a desire for radiant floor heating in an ultra-efficient home. It's one thing if they are doing it as a luxury item, but it surprises people when we explain that there may be better heating options from a financial perspective.
What was a pivotal moment that impacted the project's direction?
It was surprising how much the state of the economy played into the overall construction schedule. The original thought was that the lack of residential construction locally at the time would somehow work to our benefit in terms of construction schedule. The actual result ended up being that subcontractors were understaffed and building supply companies were under stocked. If the goal was to maintain the desired level of quality, everything simply was going to take longer to complete than we had originally thought.
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