We are working on a new, modern net zero home project on a suburban site outside Chicago. Our client wanted the design to incorporate sustainable, passive, and net-zero concepts into the final design, which we are working with them to iterate.
As architects, general contractors, and licensed real estate brokers, we can guide our clients through the process of searching for, assessing, and closing on a plot of land. The loan process for building on newly purchased land is a bit different than an existing home loan. For this project, we were able to help our clients navigate the loan process for a residentially zoned parcel.
Following the demolition of the existing split-level home on the property, we will build the new single-story, 2 bed/2 bath home with the slab-on-grade. There will be a taller clerestory element over the living/kitchen dining area, and the bedroom will surround that. A screened-in porch, with a wood-burning fireplace, for optimum bug-free, shaded comfort is part of the design and can easily be accessed from the main living area.
ARCHITECTURE SITE ANALYSIS
To start this project from the ground up, we began the way we do with all of our passive design and net zero projects: by performing a thorough site analysis to inform our Master Plan. Passive design, also known as “passive house,” is a method of approaching building construction that is very site-specific. Passive projects seek to maximize “free” resources. Resources such as sunlight and passive solar heat gain exposure, which involves measuring the angle of both summer and winter sun, when the sun is at its highest and lowest points in the sky.
THE SUN’S IMPACT ON A BUILDING SITE
Measuring and mapping solar angles enables us to plan the project’s massing so that the various rooms and outdoor spaces benefit maximally from natural light in a process called daylighting. It also allows us to design the roof angle so that solar panels installed can take maximum advantage of solar rays all year, even in the cold winter months. Installing solar panels without acknowledging the roof angle requires an investment in a rack system to hoist the panels to the appropriate tilt angle. Arranging the solar array in the direction that captures the most sun is the most effective way to generate energy and maximize output for the residence.
Working with passive solar heat gain involves considering both heating and cooling needs, especially in a seasonal climate like the Midwest. Full southern exposures pull in much-needed heat in the winter months, reducing the load on the heating and cooling systems. These exposures also benefit from carefully planned overhangs, shading, and skylights in the summer, so the family room or kitchen doesn’t become uncomfortably hot. The properties of thermal mass come into play here, providing passive benefits. Materials with high thermal mass, such as a concrete floor or stone wall, absorb solar heat during the day and release it slowly once the sun sets. And since heat follows the second law of thermodynamics, it moves to the cooler ambient temperatures.
MODERN NET ZERO HOME – FEATURES AND BENEFITS
Passive and net-zero-designed residences require a lot of thought and care upfront put into site selection and orientation, massing, insulation, heating and cooling, materials, lighting, and all energy needs. But in the end, the principles are pretty simple:
- reduce the heating and cooling demand passively, thereby lessening the need and quantity of costly technology (solar panels, larger HVAC systems, etc.).
- create a low-impact home well-adapted to its site, which is how people have been designing homes for thousands of years.
- make the home comfortable and dry, warm when it’s cold, cool when it’s warm, and populated with fresh air and lots of bright sun.
When we build a new passive design or net zero project, we design a home specific to the client’s site and preferences; all while incorporating techniques and technologies that are kinder to the planet and result in lower energy costs in the long run.
We put thought into the home’s layout and each of these elements so that the residence is warm in the winter, cool in the summer, and comfortable year-round. These passive design techniques help reduce energy bills for residents and, in some cases, can nearly eliminate them if enough solar energy is generated to power the home. A home that uses as much renewable energy as it produces is considered “net zero,” another popular term used in sustainable design. The energy the home creates can originate from various sources, including wind, geothermal, hydropower, or others, but this project will be using solar panels.
A heating method we are fond of using in our projects is radiant floor heating (RFH). Hydronic radiant floor heating involves running radiant tubes filled with heated water embedded in the floor. The system creates toasty ground surfaces, is more efficient than forced-air heating systems, and typically requires less maintenance. This is because heat rises; when it emits from the ground, it passes through the home before cooling off at the ceiling. In contrast, forced-air heating flows from ceiling vents, so the cooling process begins long before people feel it. Unfortunately, this usually means that the thermostat usually gets cranked higher and heating bills with it. We also improve on passive heating elements by considering the elevation of certain rooms, even within the home.
Concrete floors work exceptionally well with radiant heat systems because they are easy to install and cost-effective. In addition, they provide the highest performance with unsurpassed thermal benefits, which is why we feature them in so many of our projects.
Sustainable and net zero homes have numerous health and well-being benefits. A home that is properly daylighted through careful planning of maximizing natural sunlight can greatly improve mental health, mood, and physical health by supplying vitamin D and regulating sleep patterns in contrast to a dim or poorly-lit room. For people working or studying from home, many studies have shown that natural light improves attention, performance, and productivity as well, all while saving energy from electrical light usage.
Excellent insulation is a hallmark of passive design. A well-insulated envelope eliminates drafts, which can be just as costly in terms of energy bills as they are uncomfortable while also ensuring good ventilation to prevent mold and other moisture issues.
We’re designing our current suburban, single-family home with Structurally Insulated Panels (SIPS). The insulated panels, which we also installed in our River St Joe Brewery project in Michigan, are a great example of the material’s versatility since that project was considerably more extensive in scope. SIPS come already insulated to a high R-value in 4-by-8 or 4-by-10 pieces. And since they are constructed off-site in a climate-controlled factory where they are cut to the exact size needed, there is minimal on-site construction waste. They are particularly applicable in a rural setting where the labor to have framers construct a “stick-framed” structure might not be as readily available. Another benefit of SIPS is that they may be more affordable than timber due to supply chain issues.
SUSTAINABLE CLADDING MATERIAL
Choosing durable materials with great longevity properties and weather resistance appropriate to the climate is another huge component of passive design. We often specify materials that are not only durable but age beautifully, like Corten weathered steel, Shou Sugi Ban (charred cedar), which has natural pest- and mold-resistant properties, and reclaimed masonry. If a house is energy-efficient and well-insulated today, the materials should be responsibly sourced and last well into the future to be truly sustainable over the long run.
Another component of passive design, which overlaps with net zero design in that it tries to minimize energy and resource-intensive processes, is responsible water management. We, of course, opt for low-flow and water-efficient fixtures, but we employ numerous other strategies as well. For example, we like using tankless water heaters, which increases energy efficiency as the water inside the “tank” doesn’t need continuous heat throughout the day.
Rain barrels are great for collecting rainwater for gardens and landscaping purposes without asking more of the plumbing system. Allowing groundwater to recharge instead of collecting it in a drainpipe and sending it to the combined sewer system helps reduce the burden on municipal water systems during heavy rain. It can also reduce the risk of sewer overflow and flooding in Chicago. This is particularly important as climate change is set to increase the quantity and frequency of storms.
NET ZERO HOME: SUBURBAN LOT CASE STUDY
Our first priority for the case study net zero house is to reduce the building footprint as much as possible to minimize the amount of concrete and building materials required. We’ll incorporate the primary living space, including the kitchen, family room, and dining rooms, within the taller portion of the plan. The bedrooms, bathrooms, study, and utilities span the front and wrap around the public space. This layout allows for a cross-ventilation path and a higher roof, creating an elevated surface for the solar panels.
The house is slab-on-grade (no basement), which allows for an exposed, polished concrete slab with radiant hydronic heat incorporated. We’re using Structurally Insulated Panels and a rain screen assembly clad with charred wood siding to form the exterior wall envelope. The design of the windows encourages natural ventilation by exhausting the hot air that rises to the outdoors. The casements and awnings provide usage flexibility and help assist with a low U-factor, which is the rate at which a window transmits non-solar heat flow.
Open web wood trusses will cap the house (making for efficient routing of ductwork and conduit) with cavity and rigid insulation. Reducing our energy demand baseline with a highly insulated and tight envelope means the HVAC system doesn’t need to operate as often, extending the lifespan and reducing maintenance requirements.
Typical suburban houses include a prominent, street-facing garage. We’re taking an atypical approach and realigning the garage so it’s not the primary front facade feature. Instead, the garage will fade into a privacy fence and entry: a more hospitable design.
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