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The house was featured

in the 1999 

March/April issue

of Solar Today

The ABC's of Solar Living

Affordable

Electric bills, for this all electric home, averaged less than $47/month for the last 6 years.  This custom, quality home was built for less than $37/ft² in 1985.

Bright

The home is bright and warm as the winter sun penetrates deep into the home. Yet the overhangs shade the house in the heat of summer.

Comfortable

The open and inviting layout lends itself to entertaining and comfort for our family of four.  Our largest complaint from extended family and friends is that they have to pull off their sweaters when visiting, as our home stays warm in the winter.

It is wonderful to head to the mountains or lake to enjoy the beauty and peacefulness of nature.  Unfortunately those beautiful places are under stress due to pollution. Many of our highest eastern mountaintops are now barren, as pollution has damaged the vegetation.  Pollution is created by all of us, as we heat our homes, draw our baths and drive to work.  Finding ways to enjoy the benefits of our modern lifestyle while having a minimum impact upon our environment is the challenge.  Dave and Brenda Hrivnak undertook this challenge when they designed their home.

Dave, an engineer, set out to design a home that would be extremely energy efficient, easy to maintain and inexpensive to build.  Brenda sought to design a home that would be warm, inviting and fit into the typical suburban environment.  Meshing these two dreams led to many long discussions, visits to other homes and a lot of reading.  It took us nearly a year but we finally settled on a plan that we felt was aesthetically pleasing, affordable to build and energy efficient.  We think the use of natural materials on the interior; stone, oak woodwork & furniture, plants and flowers in addition to the sunlight, creates the "warm" mood that friends so often comment on.
   

We wanted to build a well-insulated, earth bermed passive solar home, so we searched for a south facing lot.  When we found a lot, our plans evolved to use it to its best potential. The lot’s original slope fit nicely with our plans and promised a pleasant view of the city and the surrounding mountains.

Combining the best of the three energy-saving technologies, we were still able to keep building costs under control.   In fact, energy efficient design features make the house appear to have more square footage.  One feature is the openness and natural flow to the patio and flower garden.  This concept makes the rooms feel larger and allows for extended entertaining space.  Our design also ensures that virtually all the square footage is "useable space", as even the hallway contains bookshelves.  Most visitors to our home don’t even notice the earth berming or passive solar features.  So Dave looks forward to a chance to explain.

Solar

We wanted our passive solar home to take advantage of the bright winter sunshine and give us a great southern view.  We also liked the simplicity of not having to open sunspaces, adjust moveable insulation, or operate fans and other active components.  Thus we designed a long narrow home to give us plenty of south facing glass.  We also chose an open floor plan to facilitate heat transfer and give the illusion of more space. Our house features about 200 ft² of south facing glass or about 12% of the floor space.  Due to hitting rock during construction, we turned the house to face 5 degrees west of due south.  We would have preferred to face the house 5-10 degrees east of south to help bring in early morning sun and give a little more summer shading.   But as a bonus, we were able to use the rock left from the blasting in an attractive landscape plan on the front hill.

The roof overhangs on the south are designed allowing no sun to hit the glazing during the summer yet the sun can penetrate deeply into the house on winter days.  We have no windows on the east or west walls and only one small north-facing window.  The first floor is a concrete slab on grade with a custom rock floor over about half of the area.  This gives us about 350 ft³ of thermal mass in the floor.  In addition we have a rock planter that acts as a room divider adding another 40 ft³ of mass.  Finally, for the strength needed for earth berming, the east, west and north walls are block filled with concrete giving an additional 850 ft³ of thermal mass.  On these bermed walls the sheetrock or  wallpaper is applied directly to the block to improve heat transfer.  This large amount of mass heats  up during the day and warms the home in the evening.  Since most of the rooms are oriented along the south wall the house is exceptionally bright and cheery.   Much of our design was gleaned from "The Passive Solar Energy Book" by Edward Mazria.  While dated it is still very relevant and useful.

Earth Berming

Our lot has a steep slope and thus earth berming was a logical approach.  But we have avoided the feeling of ‘being underground’ with the large exposure of southern windows in a house that is only 21 feet deep.  Our lot was also a bargain due to its steep grade.  These savings were a welcome offset to some of the extra building costs such as the concrete-filled blockwork. And we enjoy year-round benefits of earth berming.  The earth helps keeps the house warm in the winter, but it especially helps keep it cool during the summer.  Total air conditioning costs are estimated at less than $25 for the whole summer despite plenty of warm days and muggy nights.

  Insulation

The home is well insulated.  We have R-35 in the roof.  The south wall is a 2x6 construction with insulated sheathing for R-22.  The north, east and west block walls have 3 3/4" of expanded polystyrene that project at least 3 ft below grade.  While this is only an R-14, it is sufficient due to the thick thermal nature of the walls.  Finally we have R-5 along the southern perimeter of the slab.  Because the concrete block walls and foam insulation act as an air barrier, the house is very tight and we have little uncontrolled air infiltration.  Finally we have quilted insulating shades from Appropriate Technologies that seal around the windows.  We close these at night to bring our R-2 windows to an R-6.  The low-e glass just hit the market as we were building and we used only two such windows due to the early price premium and a worry they would block some solar gain.  When we build again we will use only low-e argon as we find the home can get almost too warm on sunny winter afternoons.   Low-e throughout would probably help moderate the temperature swings in the home.

HVAC

Traditional heating and cooling is available from a 1.5 ton heat pump with 4.5kw of back up heating, the smallest heat pump we could find.  The duct runs within the insulated envelope between the first and second floor.  We have found this investment to be a wise choice for reducing summer humidity and to compensate for cloudy winter days.

Other features

While the basic house design greatly reduced our energy needs there are other areas we addressed to make the whole house energy efficient.  The second largest residential energy use is water heating.  For this we built a breadbox pre-hot water heater.  It is simply a water tank painted black set in an insulated box with double pane glass on the top.  The water flows through the tank before it reaches the electric water heater.  This breadbox heater is one of the more pleasant surprises on the house as it works VERY well.  During sunny fall days the water going into the water heater is actually warmer than the water coming out.  Even on cold cloudy mornings it still manages to take a little chill off of the water.  We also have an insulated water heater with an extra insulating blanket.  We believe this is one reason our electric bills are so low despite Brenda LOVING deep hot baths and long hot showers!  Refrigeration also is a high-energy user and we used energy guidelines to buy one of the more energy efficient models.  Finally, whenever possible we use fluorescent lights as they use 1/4 the energy of a standard bulb so there are few worries when the kids leave the lights on.

Costs & Construction

People often ask if the house was more expensive to build than a conventional home and the short answer is yes.  But it is very hard to quantify the costs.  Dave and Brenda acted as the general contractors and performed all the clean up, insulating, water proofing and a myriad of other tasks.  We built our 3-bedroom 2-car garage home for about $64,000 in 1985 at a cost of about $37 per finished square foot.  The contractor bids at the time were $75,000 - $80,000 or about $43.50/sqft.  The going average for a modest house was $42/sqft so the costs were only slightly higher than a normal home. We also qualified for about $2,500 in energy credit rebates which helped offset the high cost of our insulating shades. While we did save a substantial amount of money being our own contractors we do not recommend that for everyone.  At the time we were young, ignorant and in love, which went a long way to counteract the MANY long and dirty hours we put in during the 3 months the house was under construction.  If you contract yourselves be sure to have everything decided upon before you break ground as most of your work is done before you ever start.  The best reference we found on home construction is Modern Carpentry by Willis Wagner & Howard Smith.

Performance

Overall we are WELL pleased with the performance of our home.  During the late fall and late spring when we use little or no traditional heating or cooling, our electric bills average a modest $36.25 for our family of 4.  In the summer they will jump to the low $40's when the total cooling for all summer is less than $25.  In the winter our bills will climb to about $70 for a total heating load of about $110 for the entire winter.  If anything, the house works almost too well as we often open a window on bright winter days late in the afternoon.  However, we consider the fresh air in the middle of winter an asset.  If we were willing to don sweaters we could probably get buy with no backup heat.  A few years ago we left 5 days over Christmas to visit family and shut off the heat.  Record cold hit Tennessee as temperatures dipped below -5 F for several cloudy days.  Many people in the area had frozen pipes.   We were concerned about our home but were 400 miles away.  We returned to surprisingly find our home a cool but livable 54 F.  We love being able to stay very warm and comfortable in the winter without ever worrying about the cost.  We have the peace of mind that we are having a minimal impact on the environment.  If all buildings were built to such standards, half the power plants could be retired giving us all something to breath easy about. 

 Would we do it again?

Absolutely!  In fact we have just purchased a lot not far from our current home and have started the process of designing a new home.  This lot is flat so we will unfortunately not be able to take advantage of earth berming.  To compensate, we are striving to improve upon our solar and insulation methods.  On the solar front we are planning about 13% south facing glass and will use low-e argon glass.  For thermal mass we will again use slab on grade and are considering using "Blue Max" on the first floor north, east and west walls.  This is a foam block that you pour solid with concrete.   For insulation we will try either structural insulated panels (SIP's) or blown in-place insulation to give a solid continuous barrier.  For heating we are looking at a very high efficiency heat pump or possibly a geothermal heat pump.  Finally we will look at a two-stage breadbox solar hot water heater as Brenda now wants a Jacuzzi tub and Dave does not want to pay more for hot water. 

The new design is looking very similar to our existing home telling us just how much we really enjoy our current design.

Hrivnak Home Project Details

Project Description: Single Family Residential Home

Designer and Energy Analyst: Dave & Brenda Hrivnak

Architect: Agnus MacDonald

Location: North East Tennessee

Size: 3-bedroom, two story 1780 square feet (outside wall dimensions)

Year Completed: 1985

Construction Cost: $64,000

Heating Degree Days: 4140

Cooling Degree Days: 1200

ENERGY PERFORMANCE

Direct solar gain meets about 60% of the heating needs.  An electric heat pump with 4.5KW of back up heat provides auxiliary heating and cooling.

SOLAR DESIGN FEATURES

Direct gain: 202 square feet of vertical south facing window area.

Thermal Mass: 1250 cubic foot of masonry thermal mass designed into the envelope

THERMAL ENVELOPE FEATURES

R-35 roof   - R-22 South walls  -  Insulating window shades on windows

Extensive earth berming on north and east walls

ECONOMIC COMPARISON

The initial cost of the house was $64,000 or about $37 square foot.  This is about $5 per square foot less than standard contractor built homes at the time, but the owners invested a significant amount of sweat equity in their home.

The following is a comparison of annual heating and cooling costs: