One of the main objectives in renovating this house is to have a "normal" utility bill while being comfortable and healthy. To do that, planning is paramount. The whole key is tightening up the structure with things like spray foam insulation, fixing the old windows, new insulated windows when possible and conditioned crawl spaces. Then comes incorporating high performance mechanical systems after lots and lots of strategizing. Having a high performing team is also essential. Here is Dean, one of the project managers from Dovetail Construction, Sean from Marshall Mechanical, Paul, the General (contractor) also from Dovetail Construction and Ben, the intern, who will be graduating from Virginia Tech next week! Go Hokies!
In its former life, the house generated heating bills that were in the thousands! When we first took "stewardship", we filled the two 275 gallon oil tanks, kept the temperature at 55 degrees and we ran out in a month! There were also TEN air-conditioning window units... It wasn't comfortable, healthy or inexpensive.
So to make things sustainable- that is to say pay the utility bill and eat regularly, a lot of engineering needs to take place. Paul gets to use his wide color palette of accent markers to delineate mechanical zones and energy loads. Everyone analyzes ductwork placement, room usage, returns, supplies, heat exchangers, fresh air intakes even the avoidance of gas boiler exhausts underneath windows...Who knew? Paul does actually...
Look at those colors!
One of the coolest (pun intended) aspects of this mechanical strategy is the use of geothermal heating and cooling. Below is an excerpt from Wikipedia about the concept. It might be more information than you can stand but if you have any questions or you want to know more, you can email me and I will ask Paul...The bottom line is that you are using the moderate temperature of the earth to heat and cool your home. Since that subterranean temperature is between 50 and 60 degrees, it takes a lot less energy to heat your house to 70 degrees say in the winter and cool it to 75 in the summer.
Very cool indeed...or hot as it were...
From Wikipedia:
Depending on latitude, the upper 3 metres (9.8 ft) of Earth's surface maintains a nearly constant temperature between 10 and 16 °C (50 and 60 °F).[4] Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat from there. Heat pumps can transfer heat from a cool space to a warm space, against the natural direction of flow, or they can enhance the natural flow of heat from a warm area to a cool one. The core of the heat pump is a loop of refrigerant pumped through a vapor-compression refrigeration cycle that moves heat. Heat pumps are always more efficient at heating than pure electric heaters, even when extracting heat from cold winter air. But unlike an air-source heat pump, which transfers heat to or from the outside air, a ground source heat pump exchanges heat with the ground. This is much more energy-efficient because underground temperatures are more stable than air temperatures through the year. Seasonal variations drop off with depth and disappear below seven meters due to thermal inertia.[3] Like a cave, the shallow ground temperature is warmer than the air above during the winter and cooler than the air in the summer. A ground source heat pump extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling). Some systems are designed to operate in one mode only, heating or cooling, depending on climate.
The geothermal pump systems reach fairly high Coefficient of performance (CoP), 3-6, on the coldest of winter nights, compared to 1.75-2.5 for air-source heat pumps on cool days.[5] Ground source heat pumps (GSHPs) are among the most energy efficient technologies for providing HVAC and water heating.[6][7] Actual CoP of a geothermal system which includes the power required to circulate the fluid through the underground tubes can be lower than 2.5. The setup costs are higher than for conventional systems, but the difference is usually returned in energy savings in 3 to 10 years. System life is estimated at 25 years for inside components and 50+ years for the ground loop.[8] As of 2004, there are over a million units installed worldwide providing 12 GW of thermal capacity, with an annual growth rate of 10%.[9]
