What is a Net Zero Energy House? In simplest terms, it is a house produces as much energy as it uses at the end of a year, thus achieving ‘net zero’ energy consumption. I have designed two Net Zero homes and quite a few that could be Net Zero if they installed solar. I take into account the sun angles on every home I design!
The brain of the home and how the home is functioning is monitored by a GE panel located in the living room area. It monitors the actual electrical usage of the home and the actual output of the photovoltaic panels at that moment and then can show daily, monthly or even yearly usage. The GE panel also keeps track of water usage all the way from watering the lawn to interior toilet and faucet usage. On the roof, we have 48 BP panels supplying the electricity for the 9kw system. Our home is grid-tied through Norris Public Power District (NPPD) with net metering. We used a Fronius grid tied inverter. If we are producing more energy than we need, the meter itself runs backwards and sends the electricity to NPPD. If we need more energy than we currently producing from the panels like on a cloudy day, then NPPD would provide the additional energy needed.
It was important that the design be mainstream and marketable. We felt that if we were able to design a home that most people would like style-wise that it would make the most wide range impact down the road. More people would be inspired to build an energy efficient home. The basic form of the home is compact and mostly linear. While a small part of the home is on the north, most of it is running east to west. This basic shape allows us to utilize the passive gain of the southern sun during the winter months, capture the sun using the solar panels and to open the home up to the Bridges Neighborhood pond views. The house front itself faces true north with the short side of the house to the east and west to minimize solar gains during the morning and late day sun. The roof angle is a 10/12 slope for maximum solar use. Our overhang extends out to two foot, six inches. This overhang is ideal to shade the strong summer sun, but yet allow for the winter sun to penetrate the interior in Nebraska. With our calculations of the summer sun angle, almost the entire first floor south wall is covered in shade during the hottest sun. We used the bracket roof overhangs as a shading device on the south basement windows. We also used this same awning detail on the west for the bathroom windows to shade the harsh afternoon and evening sun.
The floor plan is divided into two different areas. The first being the sunlight zone and the second called the buffer zone. On the south in the sunlight zone, we located the rooms we spend much of our time working, entertaining and socializing; office, living room, family room, kitchen and bedroom. In the buffer zone on the north, we grouped all the utility and private spaces that we normally don’t spend much time and typically do not require many windows. These spaces include the laundry room, bathrooms, master closet, stairs and entry spaces. They are internally located and tend to be viewed a functional or utilitarian spaces.
This is the second full net zero home I have designed. However, most of my homes are very energy efficient even if they are not full net zero. Most of them have a HERS rating of 49 or less. (A HERS score of 100 is a home built to the 2004 International Energy Conservation Code.) A net zero home has a HERS Index of 0. The lower a home's score, the more energy efficient.
This home is compact and mostly linear, running east to west. This basic shape allows us to utilize the passive gain of the southern sun during the winter months, capture the sun using the solar panels and to open the home up to the neighborhood views. The house front faces true west with minimal openings on east and west to minimize solar gains during the morning and late day sun. I provided a deep front porch for shading and to be used to enjoy the cool breezes. We also used some awnings as shading devices to help with shading in the summer on the south side.
The rooms are positioned utilizing the movement of the sun. I located the rooms that we spend much of our time on the south side of the home. The patio is on the northeast side of the home and it will be shaded most of the day so the owners can enjoy the outdoors.
The technology used is both passive and active. I calculated the sun angles to design the south, east and west sides of the home including the overhangs and window sizes. We used insulation under the basement floor, flash & batt insulation in the 2x6 walls for an R23.5 and the ceilings are R64. Windows are Low E with Passive Sun Low E on the south windows. Geothermal with vertical loops and an air exchanger (the home is built very tight) provides the heating and air conditioning. The solar panels are mounted on the roofs. Low energy and water usage are used throughout the home.
Featured on Houzz: The Neeman Residence, The Barn Project (Two Times) & The McClellan Residence
AIA Nebraska - People's Choice Architecture Interiors
Project: The Barn
Best of Houzz Awards
Michelle Penn, AIA
8111 Preserve Court
Lincoln, NE 68516
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