This building is located in Northern New Hampshire at about 1600 feet elevation so winter is a major part of our year. After securing the building envelop, utilizing passive solar heat gain as much as possible and recycling existing heat within the building, we will then turn to other sources for heat.
We are utilizing six different and complementary heating systems. We do have a built in redundancy but not necessarily duplicity in costs. This is not as flakey as it sounds so follow me on this one.
Passive Solar (Heat System #1)
The passive solar rule of thumb says to face the building due south. Well, what if a view of a 160 acre pond is directly east? This was a tough one, but not an unusual dilemma for situating a building. We ended up facing the building 45 degrees off direct South, which will give us a view of the pond from all of the rooms. This trade-off will cost us passive and active solar gain but will give us an incredible view. We have also done computer modeling studies showing us shading effects for different times of the year and times of the day. Combining our building orientation with window placement, window sizing and glazing, roofing overhang design, window shutters and space layout has aided in optimizing our passive solar gains in the winter and deflecting in the summer months.
Radiant Floor Hot Water Heat System
The main floor and second floor of the building have radiant tubing imbedded in a thin layer of lightweight concrete combined with an insulation layer and then hardwood flooring.Hot water is pumped through the tubing which heats the cement like a heat sink storage system and then radiates through the building.With this type of heating system we eliminate most of the stratification differences and space fluctuation of heating a building.Bottom line is that your feet are exposed to the same temperature as your head.The air is not the only thing that is heated, the whole inside of the building is heated.This is especially helpful in the main floor with its barn-type design that is open 30 feet up into the cupola. This radiant floor system uses a 700 gallon super-insulated hot water storage tank as its heat source.There are a number of ways that we heat this hot water storage heat sink.
Solar and Excess Electric Hot Water (System #2)
Our primary electrical needs are supplied by a photovoltaic solar array built into the roof system.When our electrical needs for the building are met and the battery bank is full, the excess electricity is channeled to a hot water storage tank that is used for the radiant floor heating system and domestic hot water.When the hydro electric system is online the excess electricity generated will also go to heating the hot water storage tank.
Masonry Heater (Heat System #3)
In the 17th century most buildings were heated with wood, but in Europe the wood shortage created such an energy crisis that the kings in Prussia, Sweden, Norway and Denmark ordered their craftsman and architects to produce better woodstove designs. This concerted effort produced radically new heat-storage masonry heater designs, which showed enormous improvements in efficiency and corresponding wood conservation. Many of these have survived hundreds of years and are still in use today in Sweden, Austria, Finland and Germany. Masonry heaters have been perfected so much that the Finnish government encourages the use of them today through tax incentives to reduce the use of natural gas, oil and electricity. The result is that 90% of the new homes built in Finland are heated with a masonry heater.
The masonry heater design we chose gives us the ambiance of a fireplace but the heating capacity and energy efficiency developed over hundreds of years in environments that demanded production or else they simply froze to death. Since we live in a working forest, the most prevalent and renewable natural resource other than sun is wood.
In a nutshell the concept of these heaters is that you light them twice a day, morning and night. The firebox design allows the short fire to reach temperatures of 1500 degrees, which in turn heats the massive masonry and rocks that make up the heater as well as burn the wood gasses so completely to give combustion efficiencies in the 90% range. The heated rock radiates heat throughout the day or night.
The Masonry heater does not need to use the radiant floor system to heat the building, it uses its heated masonry mass as a storage system. There is a water line running through the masonry heater that can be used to heat a hot water storage tank if we choose to.
Tarm Wood Fired Boiler (Heat System #4)
The Wood Boiler we use is manufactured in Denmark and distributed in the United States by a company called Tarm USA that is located right down the street from us in Lyme, New Hampshire and operated by the local Nichols family. This boiler can either use cord wood or another model can use corn or wood pellets. The concept is similar to the masonry heater. You light the stove once or twice a day in the winter and the 1800 degrees fire heats the 700 gallon super-insulated water storage tank. The hot water is used for the radiant floor heat and to heat domestic hot water for showers and washing. This high temperature, like the masonry heater, efficiently burns not only the wood but the wood gases as well.
Looking to burn wood efficiently and in an environmentally sound manner will allow us to use this resource that is literally all around us without a dependency on anyone. If we can utilize a renewable natural resource like wood from a sustainable forest and use it in a manner that will not add CO2 to our greenhouse issue or acid rain as well as stay away from burning fossil fuels, then we do less harm to our environment and lessen our fossil fuel dependency.
Natural Geothermal Heat (Heat System #5)
The design of the Barn House uses the concept of a bank barn, whereby the lower level backside is situated on a slope in the landscape. This was used so that tractors and livestock could enter the building on the backside of the barn and the other three sides of the lower level are below ground. The lower level of the barn house is 12 feet below ground level on three sides of the building. Ground frost in this part of New Hampshire usually goes about three feet in the ground, below that point the earth stays around 50 degrees. We will therefore be using the natural thermal insulation of the ground to keep this level of the building above freezing.
We will admit that to us this concept sounds a tad sketchy and I sure hope it works because the water system for the whole house originates from that lower level. I guess we will find out this winter if our water pipes freeze or not.
Propane Furnace and On Demand Hot Water (System #6)
Well, if the solar or hydro electric systems are not generating enough electricity to heat the hot water storage tank for our radiant floor system and we are too lazy or not at home to put wood into the Tarm Wood Boiler or the Masonry heater, then the high-efficiency propane furnace will kick in at a predetermined temperature. We chose a Viessmann combination propane boiler and on demand hot water system to not only act as our backup system but will also be the control and monitoring system for our heating system. The Viessmann system has an efficiency of up to 98%.
Heat Recovery Ventilator
When Foam-Tech finished insulating the building they performed a number of tests to insure that the building envelop was sealed. After all of the testing the manager of Foam-Tech was kind of disappointed because he calculated that there was still 9 square inches of leaks in the building. He knew where most of them were and had a plan to plug them. I had to smile at this type of dedication; counting the lower barn level this is a three story building with 2800 square feet of livable space and this guy is upset about the 9 square inches of air leakage that are probably coming from the electrical conduit that is still open and the masonry heater that isnít completed yet. He of course insisted on coming back when these things are completed so he could run a decompression and thermal imaging test again. I bet if I am in that building when he decompresses it I am going to need an oxygen tank to breath.
When a building is super-insulated as this building is you actually need to bring fresh air into the building during the winter because it is so tightly sealed. In bringing the fresh air in you also need to let some of the inside air out but you want to recover the heat that is in that inside air. Thatís the job of the heat recovery ventilator. Each room is equipped with a fresh air vent and an overhead air mask that drops down in case of malfunction.
Water Drain Heat Recovery System
Recycle, Reuse and donít waste. Now this one seems a bit of a stretch to me but the engineers tell me it works. When you take a shower, wash cloths or do dishes the hot water that goes down the drain is a waste of energy. Through a simple system of coils in the drain system, the energy embedded in the hot water that is going down the drain is recycled and returned to our hot water storage system. Now the water is not recycled at this point, the heat is. My first reaction was give me a break, how much heat could we recover and what does this heat recovery coil contraption cost. Well the contraption (technical term that means I donít know) wasnít that expensive so I said ok. This is a small one we are taking on faith but we will put this on our ďto be verified listĒ. Remember, this building is a model where we are testing different conservation concepts and we need to have an open mind. I just want to make sure it is an open mind we have and not just an open wallet.
Hot Water Recirculation
Here's the deal, every time you turn your faucet on you usually run the water until it reaches a specific temperature therefore flushing perfectly good water down the drain as well as the embodied energy in the hot water that is not hot enough for you. With this devise you press a button and the water that is sitting in the water line is recirculated back to the tank so you have fresh hot or cold water instantly when you turn the tap on.