The Kosmer Solar House

How It Works

$2.50 A DAY HEATS THIS NEW 4000 SQ FT. SOLAR HOME -- The promise of the 21st. Century home delivered. *


Affordable for mainstream America to build and own, this super energy efficient conventional 4000 sq. ft. home was built for about $125.00 a sq. ft: about the same cost as a traditional new home. Dollar for dollar this traditional style home, built from proven solar technology with a 30 year performance record, far exceeds the cost-to-benefit ratio of any “green” or "zero energy" home today.

The Kosmer passive solar house incorporates the latest iteration of nationally recognized Solar Engineer Bruce Brownell’s solar heating design as well as energy efficient and renewable resource “green” technologies. This passive solar house is the culmination of a proven solar technology Bruce Brownell developed and refined during the past thirty years in over 300 solar homes. He has said of his homes, “The sun has never once ever sent any of my clients a bill”. The 4000 square ft. home is estimated to have heating costs in the $900.00 to $1200 range per year (assuming Crude oil is $100 a barrel) in the cold climate of Upstate New York in Fly Creek, just outside of Cooperstown (of Baseball Hall of Fame renown). The home’s energy efficiency demonstrates that if a passive solar home can work in this climate, it can work anywhere in the United States.


Passive Solar Heating By The Sun - A Proven 30 Year Record

The cost to heat this mainstream traditional style home is so low because the sun is responsible for the lion’s share of providing heat. The house retains that heat by being totally encased in a super energy efficient shell of 4”thick rigid polyurethane insulation, not only on the exterior walls, but also beneath the 12” concrete slab and on the roof (fig 1 & 2). Using rigid insulation around the entire house is like building a soda picnic cooler, except you’re the soda.


Figure 1 1 ft. of gravel is used under the concrete slab with 3 ft. gravel footings around the perimeter of the slab. With drainage pipes in the gravel, Tyvek is laid out over the gravel and then a high tech pool liner is applied over the Tyvek (white sheathing seen in photo). These procedures are undertaken to prevent water & humidity migration into the concrete slab. Over the pool liner, two layers of 2” thick foil covered Dow Tuff-R rigid polyurethane insulation are laid out and foil taped at joints, staggering the joints on each level before the concrete is poured.

Figure 2 Dow Tuff-R rigid polyurethane foil covered insulation being applied over the sheathing of the house. 2nd layer of insulation has been applied to the front south wall of the house about half way up the 2nd story windows.

Top-of-the-line Simonton ProFinish ENERGY STAR qualified low E double glazed windows and their correct placement for maximum solar gain and minimum heat loss along with 4” of the rigid insulation combine to form the perfect thermal envelope to retain heat in the winter and resist heat in the summer. A state-of-the-art ENERGY STAR qualified Baxi Luna 3 boiler (fig 3) and Baxi solar hot water panels (fig 4) provide supplementary heat during the coldest periods.


Figure 3 ENERGY STAR qualified Baxi propane boiler (white box on wall) provides both domestic hot water and closed loop hot water for heat. John Carrigan, owner of BUILDING WITH INTEGRITY, standing next to the utility wall is the contractor for the house. Note black tubing on ceiling. It is Pinnacle Supply’s high tech insulated double line water Time Saver Pipe. The tubing carries antifreeze/water mixture from hot water solar panels to a holding tank in utility room, with virtually no heat loss, where it heats domestic hot water and closed loop hot water for heat. *

Figure 4 Baxi hot water solar panels preheat hot water to minimize or eliminate the need for the Baxi boiler to turn on to provide hot water thereby minimizing propane usage. *

The beauty of this solar heating technology is that its ducted air heat transfer system can be designed and incorporated into any style new mainstream conventional home plan as it was for this home. This technology has taken solar homes out of the realm of off-the-grid odd-looking structures designed for stripped down economically defensive living. These mainstream market solar homes have arrived as a unified home lifestyle and architectural style statement similar to the evolution of hybrid cars in the auto industry.

First coming to prominence during the gas shortage days of the Carter Administration, Bruce Brownell’s passive solar systems designs have now come of age in the 21st Century where crude oil has gone from below $40 a barrel through the $60-$70 a barrel range and is assured to blow past $100 a barrel. When you consider that this passive solar home costs about the same as a comparable traditionally constructed home, you can understand how this home has made new traditional home construction obsolete before these new traditional homes are even built. Passive solar homes like ours can have the same impact for 21st century sustainable subdivisions that Levittown had by creating the original sub-division. Public awareness about these passive solar homes will create the kind of demand that can re-invigorate the home building industry for the foreseeable future.


Heating Costs Verses Total Energy Costs

When a home is this efficient in retaining heat, everything helps heat the home - not just the sun and the supplementary heating plant. Your lights (regular and energy efficient bulbs), appliances (including ENERGY STAR qaulified appliances) and even your body heat contribute to the heat gain of the home. This heat gain is not negligible because the heat loss from the home is dramatically less than the heat loss in a traditionally built home. Add a state-of-the-art wood stove and the heat gain is spectacular. You will also use less electricity in the home because you will have much more natural light more of the time. So when you actually compare total energy costs of a traditional home (heat, gas, electric) verses this passive solar home, the difference in energy costs becomes more dramatic than the headline $2.50 a day heat cost.


Maximizing Solar Gain & Providing Even Heat Distribution

Unlike earlier passive solar homes noted for their uneven heat absorption and distribution cycle, this passive solar home uses a ducted air heat transfer system. Air ducts run through the 1 ft. thick thermal mass concrete slab (fig 5) and throughout the home that constantly have air circulating through them.

Figure 5 After the ductwork and main duct trunk are laid out and bolted down to the 2” slab, the top 10” of concrete is poured, encapsulating the ducts in a 12” concrete slab. This slab is the thermal battery that stores and releases heat into the house.

Instead of solely relying on the sun to warm the surface of the thermal mass concrete slab (usually unevenly, mostly on the side of the floor facing south were there are windows), the ducts take the heated air in the house warmed by the sun and store it evenly throughout the body of the thermal mass concrete slab. A large squirrel cage fan draws the air down a vertical shaft (fig 6) from the air return grilles in the attic and then pushes the air into the main trunk duct and its tributary ducts dispersed within the concrete slab.

Figure 6 Large squirrel cage fan is on 24/7 during the heating season pulling air down from the attic air return grilles through the HEPA-like filters (just above the light bulb). It pushes air through the box beneath it to the ducts below in the concrete thermal battery that is the slab of the house. The box contains a horizontal hot water radiator. When the house requires auxiliary heat, the Baxi boiler provides hot water that runs through the radiator. The air passes through that heated radiator and picks up supplemental heat for the house.

From the slab the air travels back into the house up air ducts that open on every floor. The net result is a concrete slab being heated on both its surface and interior (instead of just the surface) much more efficiently and evenly. This duct system allows the thermal slab to act as a more efficient thermal storage battery, storing more heat and storing it more quickly and evenly than a passive solar home without ducts. In the cooler evening hours, while the concrete slab is releasing heat from its surface, those ducts draw heat from within the heated thermal concrete slab and evenly deliver heated air to the whole house.

Passive solar homes operate on the simple physics principal that everything wants to even out to the same temperature. Pour hot coffee into a cold mug and within minutes the mug heats up and the coffee cools down until they are both the same temperature. That principle describes how the 1 ft. thick thermal mass concrete slab solar storage battery works. During the day, when this slab is colder than the house, the slab absorbs heat (much of the heat is generated by the sun warming the air in the house). In the evening, when the slab becomes warmer than the house (as the house slowly cools down in the cooler evening hours), the slab releases heat. Bruce Brownell’s ducted air heat transfer system and thermal shell design optimizes the efficiency of this heat transfer and dramatically minimizes heat loss.