This diary covers the planning, building and operation of a Greenhouse/MiniEarthship in Central Pennsylvania, and the measured impact on home heating etc.
It is offered in honor of COP26, or perhaps offered in contrast, as it documents a measured reduction of fossil fuel footprint for one place, at one time (and increases very local fresh vegetable consumption at the same time.)
Executive Summary: We used Earthship Principles to design and add a 144 sq ft greenhouse (augmented by multiple heat capture systems) at a cost of $3663 to our 1932 house. After one year we know on any sunny day through late Nov and from Mid-Feb onward we can generate enough thermal energy to heat our entire house and shut off fossil fuel and electric heat pump systems. Late November — Mid-Feb the system supplements our heat pump system. I am gathering day by data, but estimate our overall systems (Solar+HeatPump+MiniEarthship) have reduced this homes GHG impact by apx. 85% annually.
Acknowledgements.
First. I apologize to the hyper-precise reader for what are, I am certain, many horrific errors in my carbon balance calculations, engineering summaries etc. I am only an applied physicist by training and engineering executive by profession, and though I have done my best to use accepted formulas for the carbon costs of various inputs on our project, my understanding is only that of an enthusiastic amatuer in the complex field of civil thermal engineering and carbon offset costing.
Second. All Credit for this project goes to my Wife, my Son, and the fanatics who run various EarthShip Web Sites. My wife, for two decades, has longed for a Greenhouse to allow her Gardening addiction to extend beyond seed-catalogue porn during the winter months. My son, who is obsessed with eating fresh cherry tomatoes, insisted he would help with “all of it, every bit” if it meant getting closer to year round fresh tomatoes. And may the great FSM Carress with Noodly Appendages the Earthship fanatics around the world who post and maintain insights, plans, feedback and tricks. Our effort is tiny compared to many of these giants, but I avoided major mistakes and improved my planning by spending a few evenings reading their sites, reports and input.
Third. I would like to thank SARS COVID19, who kept us in lockdown at home, put every business meeting on Zoom, ended nearly all the wasteful and carbon dioxide producing business travel, and … put me at home for a Pandamic so I could then say…. “Okay, we are here. How about a Greenhouse Project?”
And Fourth and Finally. A respectful tip of my hat to Gaia and Sol. They provide us with an amazing habitable world, orbiting a massive, scary and growing thermonuclear furnace. It’s an honor to be a parasite feasting on the outputs of their creation, and it’s been fun working with them on this project. I doubt they care, but you never know.
Pre-Planning $0.
Different people have a range of opinion about what is a “comfortable” home temperature. Many might find our tolerances outside of their envelope. Others the opposite. In winter we allow our home to drop to 50f at night. We set thermostat for 58-62f during the day. We lived for two decades in house with no AC in summer. Our “new” home (going on five years) we have a heat-pump system which can both heat and cool. We have used the cooling twice. Our former home, and “new” home are both older construction (1918 and 1932). We invested in maximizing insulation/R Values in both. When purchased, our “new” 1932 home had Oil fueled hot-water heat as the primary heat source with a Natural Gas sealed fireplace with blower as a backup. A mini-split heat pump was in place primarily for cooling in summer. In our first year of ownership we added a 12 panel solar array — grid tied, and generate apx. 80% of our power usage. Upgraded the heat-pump and optimized it for heating. Improved insulation. Replaced a older electric hot water heater with a modern humidity/heater combination hot water system (50% less electricity use for same home water volume). From the time we purchased the house — we considered that “someday” we would figure out how to add passive solar heating — likely by way of a shed-style greenhouse. So… you are caught up.
Earthship Lurking $0.
If you don’t know about Earthships. Google is your friend. Taos is your Mecca. Santa Barbara is the working goal. In short, it is a movement, architectural, cultural and social to build structures, and lives, integrated into a place and space that give back to the Earth. Most Earthships use little or no fossil fuels and are built with a minimum of carbon inputs. Often they are built in “fleets” to support one another. These folks are serious innovators in Straw-bale, Rammed Earth, Passive and Active Solar, Water Recycling and Local Fooding. They all appear to be very cool folks. Sadly, I am just not that cool. But I love their world (and lurked into their Earthships, and came away with lessons, ideas and system principles developed by the Earthshippers. They are extremely applicable and usable even by the uncool folks like me augmenting house-heating with a greenhouse kit. Here are my key learnings:
1 - At mid-latitudes the optimum ratio for the Greenhouse/GlassWall portion for Solar-Thermal collection to the Living Space to be heated is apx. 25%. This needs to be calculated in CUBIC FEET, but Sq Ft of collection space is a close approximation. My house is not a bermed rammed earth WonderShip integrated with it’s solar collection wall. It is rather a 1932 3 Bedroom Cape Cod with a 1992 Family Room addition sticking out one side. This brings with it an added challenge of how to get the heated air from the greenhouse to “communicate” with the main house. This was actually not well documented by Earthshippers who are very understandably too cool to discuss retrofitting a house like mine. But I found great resources on this problem through Palram Corp - who eventually supplied our Greenhouse Kit. More on that below.
2 - Thermal Batteries are BOSS in cold climates. In short, BEFORE you build the greenhouse, you dig under the greenhouse location, and add either air pipes or water circulation pipes which pull excess heat from the Greenhouse into the ground by day, and then return that heat to the Greenhouse at night.
3 - Berm/Kneewall the glass base. When it is cold outside the 6-12” closest to the ground is often 5-10f colder than the air just above the ground, and that falling cold air works hard to move sideways and “fill” everywhere it can. Don’t mount your greenhouse to the ground, cold air will pour in through the bottom and find every crack it can. Dig a foundation downward, and then a knee wall up, make that kneewall nsulated or at least cold-resistant and make sure the glass starts at least 6” UP from the surrounding terrain. If possible make sure the terrain at the base of the kneewall is sloped away from the Greenhouse to “shed” the sinking cold air away from the greenhouse.
4 - Full Sun Overheat Danger. The Earthship community and the less-cool group I am in “I built a Greenhouse KIt” community will ALL tell you the same thing. VENT or DIE. You can incinerate yourself, your plants, and whatever else is in a Greenhouse or Earthship if you don’t build systems to shed excess heating on Max-Sun Days. Even Mid-Winter Max Sun Days. (Note, as a test, in June at 10AM I sealed the Greenhouse and dissabled the automated vents. The temp rose from 90f to 122f in 4 minutes - which I suppose is a Greenhouse Living experience I should offer world leaders as a preview of much of America c. 2050. Below I detail the FIVE systems we have in place for thermal management.
5 - Water. Greenhouses are thirsty. Very very thirsty. Plan on how to get 2+ gallons per 100 sq ft per day into a fully active greenhouse.
6 - Aphids. You may think you are building a Greenhouse for you. But you are not. You are building an Aphid Spa and the local Aphid’s will be extremely pleased. Choose your bio-predators and nematodes in advance and think through pest management. We went with Ladybugs. If you don’t know, the Larva and Adults eat aphids, scale, thrips etc. Be aware the adults have very powerful jaws and can and will bite you from time to time. But they are really pretty, and fun, and we really enjoy watching them waddle along the plants hunting aphids. And they are native in our area. (Note...I live in Pennsylvania. Some of the Earthship folks do not just have problems with the Aphid Spa issues, I read about management techniques dealing with Scorpions, Snakes, Dessert Rats, Bats, very poisonous Spiders etc. etc. Yea. Not it. But literally everyone who builds these has to deal with Aphids - some even encourage the Scorpions, because the baby Scorpions apparently feast on aphids. But once again, I am not cool enough to knowling breed and cohabitate with Scorpions.)
7 - Permits. Permits are key. Whether you build a stand-alone greenhouse or as we did “a Directly Adjacent But not built as an Addition to the House” or maybe you are that cool and will build a full Earthship for you and your Scorpions, but in any case - if you are doing it where zoning exists - Permits. Figure that out early. Permits are key.
PLANNING $0
Many fools - including me - have roughed out on paper perfect and ultimate DIY Greenhouses. And all of us fools have Tubed in the YouTube-i-verse and watched fellow fools build DIY Greenhouses. In my case I even have enough engineering and building skills in my DIY design to realize how many things were going to be very hard to work out as a DIY. I have built four homes and numerous other structures from scratch. Greenhouses are deceptively complicated. They are extremeophiles from a construction perspective. They have dozens of points of failure and points of extreme and accelerated decay and material stress in many places. I would bet 90%+ of the perky YouTube DIYs systems are toast and sent to the trash in a 1-10 year window. Why? Physics. Greenhouses not only harness A LOT of thermal energy (much more on that below) but they are exposed to extreme humidity swings, extreme elements, very high wind-load vs. structural capacity and they whiplash between those states very fast. Materials, joints and systems fail when they swing between extreme conditions quickly. After many sheets of graph paper, I chose NOT to use my DIY skills to design the whole system, and instead I trusted in the super-smart engineers who design these things full time at Greenhouse companies. If you get serious about this idea, look deeply at their designs, you will realize how many things you really had not considered. But I kept all my weird site-specific, thermal battery, arbor design and dryer wet-waste-heat ideas, and build the in and mostly UNDER a professionally engineered greenhouse.
So, 50+ pages of graph paper, 20 YouTube DIY bookmarks (none of whom show what it looks like 5 years later) and two library books on Greenhouse building later, I put spoke with two engineers with decades of experience figuring out a lot of the things I was wondering how to solve at Palram. There are several great greenhouse companies to consider. I checked out several. Palram was my pick as best. They have tens of thousands of units currently installed worldwide that have lasted for decades AND they have some very interesting additional value ads.
(If you read this, and agree with me that I am a fool, and you go ahead with your DIY design- please do not forget to work out: Expansion joint rates of your materials, snow and wind loads, materials jointing, fastener capacity and corrosion rates in projected conditions given mixed metal and plastic chemistries and of course automated opener systems. These all caused me serious pause. And cost. My DIY design, which had missing things still to solve, pencilled out as more expensive than fully engineered kits. Oh. And Permits. See Below.
PALRAM - Some thoughts before I started spending money.
I don’t work for them. I don’t get paid by them. I bought my kit just like thousands of other customers after looking at many options. They are an Isreali company with subsidiaries worldwide. Some of the company founders came from the Earthship Community, and they have a corporate goal to design the world’s most optimum polycarbonate commercial and residential greenhouses. And they are doing a pretty good job of it. I was impressed by the substantive sustainability policy and goals and Palram’s constant ranks with the top performing products in the category. Reviews (and my personal experience) is they build super-durable kits, replace parts I broke no questions asked and provide great advice.
Palram kits and parts are stocked by Costco, Lowes, Wayfair, Cabellas, Amazon etc. etc. The company offers dozens of configurations with many options. They build systems from mini-houses you put on a patio all the way up to Multi-Acre commercial grow houses for commercial cannibus/flower/veggie growers. My experience was they were very generous with Customer Support time and testing data - if you are like me and ask for it. As it turns out one of Palram’s US based manufacturing facilities is near my home, and they even confirmed the twin-wall polycarbonate in my kit was locally made material. They got me data on energy and input costs to manufacture and deliver and their calculation is my unit cost 2.2 tons of GHG emissions mostly CO2 to manufacture. This number seemed low to me, but they had pretty solid numbers and economy of scale...is...economical. In any case, that is about the same GHGs as an average home in PA using Oil heat uses in one winter. If you want to play with GHG discharges of various “normal” I encourage you to go enjoy the EPA site dedicated to fools who enjoy such things.
https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references
THE UNIT I WANTED VS THE PERMIT I COULD GET - AND THE UNIT WE ORDERED TO MATCH THE PERMIT MAXIMUM SIZE - $2331
My DIY design was a longitudinal angled shed style. It would have been 18’ along the house and come out 11’6” from the house. It would have been 12’ high against the house sloping steeply down to 5’ tall away from the house. I designed a 6” knee-wall foundation and two 16’ thermal battery tubes set 2’ and 4’ below the greenhouse. The tubes were charged by a small solar powered fan, and warm air was pulled out by a thermostat switched low voltage low speed fan. So with my DIY layouts, foundation design, and tear sheets for two kit options from Palram I called the local township offices to determine what permits were needed for this adventure. BTW, locally we were then in full Pandemic Lockdown.
They were really helpful and really happy to help. I already pre-pandemic installed Solar (prior diary) and pulled permits for other reasons, and I came with solid information. But in brief, I was told building ANY option over 144 sq ft would be too big for “a simple” shed/greenhouse permit and would require both an engineering stamp, a Township Construction Permit and a potentially cumbersome COUNTY level permit and design compliance review. It would also require a non-commercial Agriculture letter and some other compliance bits and bobs. By the end of the Zoom call, it was clear if I could come back with a design under 144 sq ft, under 10’ in height and not structurally connected to the house (they can touch, but not be structurally integrated) - then the township could issue a simple permit for $32 and now waiting or meetings. I also learned if I was going to do ANY DIY approach over 144 sq ft, I would need both an architect stamp and engineering calculation for wind and snow loads. The permit lords ended any interest in DIY. But a kit that comes with permitted wind and snow load calculations. So to the internet and notepads.
As I shared above, via the Earthship community, I knew if our mini-Earthship Greenhouse was going to heat my entire house in mid-winter, I would need apx. 400 sq ft of thermal collection footprint with excellent “communication” — air flow and/or liquid flow — integration between house and greenhouse. My available space, and various physical limits only allowed apx. 200 sq ft of collection footprint. My DIY Design was 212 sq ft. I calculated that design could heat the entire house through November 25th, help augment heating through mid-winter days, and return to being fully capable of heating the house apx February 10th. Midwinter would require our heat pump to keep the house warm.
At 144 Sq Ft the heating potential obviously shrunk. My home-built-rough-order-of-magnitude (ROM) calculator indicated we would be able to heat the entire house through Nov. 10th, augment heating during the winter and fully heat the house again around March 1st. And of course we would have 25% less space to grow food, but I was pretty sure a 144 sq ft greenhouse could be the sole heat-source for our house 60-90 days a year which otherwise would need other heating, and serve as a partial heating source on any cold day in which the sun shined. This turned out to be correct. I also considered that winters are becoming increasingly mild in our region, but also increasingly cloudy, which means over the next ten years we have one factor I projected made a 144sq ft capacity MORE capable of meeting our needs and a second factor which made it LESS capable. In any case, we move on.
We played with photo-superimposing tools to examine what several kit greenhouses would look like. Interestingly we decided to completely dump the “shed” style designs which seemed awkward when cut down to a smaller 14x10 dimension. We instead liked the look a “barn” style greenhouse with a more wrap-around experience with the light and a door at the far end. It also allowed us to make an arbor and porch at the end and surround that with herbs which like lots of reflected light.
Our choice eventually became the Palram Americana 12x12. It fit exactly in the maximum permit envelope. Allowed for my knee wall and thermal battery design. While designed Palram as a free standing unit, I was confident I could easily remove the door-free end-wall and abutt it to the main house side door allowing us to simply open the door and let in heated air, or walk out into the greenhouse with our morning coffee. Please pause and enjoy the groovy promotional video of the unit c. 2010, which made us chuckle before we ordered. It still makes me chuckle.
https://www.youtube.com/watch?v=ty5y6IYK5yc
With Palram spec sheets, wind/snow load certificates done, we just need to marked out on the wall exactly where it would fit place boards to layout the floor shape including the arbor and patio steps and shoot a picture. Doing this test layout, we ended up sliding the entire unit about 2’ off center of the door to the house, allowing for a larger growing area to the left side and a more of a sitting area and bench to the right side. Picture, Forms, Certificates ,$32 and township forms submitted. Approved while I stood there.
ONLY THEN, with permit and approvals in hand, did we order the Greenhouse. We got a great price from a smaller vendor who was selling the last unit they had in stock. Complete Palram Greenhouse Kit, including a passive hydraulic opener and extra shelving which he warned us for a “different kit, but all Palram stuff fits” — $2299.00.
MiniExcavator Weekend. $570
Call 511 before you dig. Good thing we did. We knew where out sewer line was, but found it about 6” before we thought we would, but as it was marked by the 511 utility folks and we were being careful — it worked as it should.
We had a rented a mini-track hoe for a weekend. $280. We dug 18” footing trenches and dug two channels for 4” drainage pipes to become our Thermal Battery at 24” and 48” underground. We also did some work on a failing retaining wall. It was about 4 hours of excavation for the Greenhouse, and a lot of fun for our 8 year old son. I then cut ¾” plywood to made concrete forms, drove in rebar and hit our only delay. Concrete. Cost of rebar and wood for forms $290
Pouring Concrete. $350
Now late summer 2020 our local concrete mill was slammed. We wanted a partial load of 6 yards. 2 yards for our greenhouse footing/knee wall, 1 yard for a patio extension and 3 yards to repair that failing retaining wall on our driveway. As a partial load we were last-priority and got pushed back twice for mixer time. After the second time, and three lost weeks of waiting, I found a couple people with smaller projects and agreed to swap them helping me on my project for all the concrete they could haul away. I changed the order to a full truck order and locked a date — then mid-september. Concrete truck deliveries are very time sensitive and there are a lot of ways to mix concrete. Do your homework. Prep your site. Line up help. You have a limited time to keep the concrete from setting and a limited time the truck will stay on a job site. We booked 3 hours, and the greenhouse was NOT near the roadway. So we had to shuttle back and forth with lawn tractors towing trailers. Each trailer could carry about ⅛ a yard of concrete. Concrete is heavy. So it was...work. My neighbor and friend Craig was tractor driver. In exchange he got a couple loads for footers at his house. I shovelled and leveled. We went over our 3 hours by 15 minutes. But our local concrete firm was cool about it - if you are using concrete for a footing be aware this can be a logistics challenge. You can hand mix concrete from bags. But that is much more labor intensive process, and even when done perfectly is not easy to get high quality concrete.
Two days later we pulled the concrete forms and backfilled dirt around them. We now had a level, solid base 3” above the ground, and 18” below the ground. I then recut up the concrete forms and pressure treated 2x4s to make 6” tall knee walls on the top of the concrete footer. This places the metal base on a level 2x4 footing 9”+ above the outside ground, which was, per the Earthship mentors sloped away from the house to shed cold air. It works BTW.
Using concrete adds to the project Carbon footprint apx. 400pounds of C02 per yard of concrete. So add 800 pounds of CO2 to Gaia for our footing.
Assembling a Palram Greenhouse.
Palram assembly is like IKEA, but supersized. Our unit has a 106 page no-words all picture manual, and a separate 32 page english manual, and some separate data sheets. And materials sheets. And inside the four boxes with about 1000 parts, there were several additional sub-assembly sheets. It all came by common carrier and weighed about 400 pounds. The family laid out all the parts in an order that made sense to us. I read the manual through twice, and modified a number of steps where I knew I planned to remove the rear wall. Which turned out to be about the degree of difficulty I expected. Three days later it was more or less assembled. Several more weekends of detailing, planter assembly, refinement and wiring followed. It was working as thermal heating source in time for the first chill nights of October 2020. And it worked.
Thermal Control Systems $162
In full sun our little greenhouse generates a LOT of heat. As I shared above in June, at 10AM in full sun at only 65f outside, it takes only 4 minutes to go from 90f inside the greenhouse with full vents open to a scorched earth 122f. In Fall, Winter and Early Spring Old Sol is lower in angle, but as soon as it hits the greenhouse, the temp leaps 30f-40f above background temperature in under 5 minutes. Here is a link to a spreadsheet my son has been keeping for his class tracking temperatures inside the greenhouse, outside house and several locations throughout the house this fall. He is documenting for his virtual school how we heat our house using only our Greenhouse this time of year. In summary, with 6-ish hours of winter sun it heats the entire house while the sun is out, and over the course of the day adds 1-10f to every room in the house, depending on how close it is to the very warm doorway. Here are the Systems we use, and basic notes about how they perform for heat management.
1 - The Side Door. The Greenhouse is built immediately next to the side door to our house. (Per permit and zoning, our Greenhouse is NOT structurally integrated with the house. It is wholly structurally separate — immediately next to our house.) The side door, rarely used by us previously used to lead out to a well on the property when the house was first built. Prior to public water in the 1940s. Our primary heating control October-May to both cool the greenhouse and heat our main house is we just open the door when the sun is out. The greenhouse in the sun with the door open will hold 30-70f above the external temperature, dumping excess heat into the house via the dining room stairwell. We will often place a fan in the doorway to force more hot air into the house. Today, as I write this it is 58f outside, 96f in the greenhouse, the door is open and a fan is on. The house temperature ranges from 60f in my office to 78f in dining room temperatures will continue rising until around 330PM when the sun will sink below the roofline of the neighbors house. We will close the side door. It is predicted to get to around 38f tonight. The greenhouse will hold enough heat to remain in the 50s tonight until the sun hits it around 730 AM tomorrow. Our house is extremely well insulated and will likely be in the 60-64 range when we open the side door tomorrow for the next injection of solar heat.
2 - Underground Thermal Battery. Earthshipper are right. It is a Boss. I rigged a tiny 15Watt solar panel to a salvaged computer cooler fan attached to the input end of the Thermal Battery tubes. It pulls air from the hottest point of the Greenhouse (often over 100f) anytime it is sunny and hot it flows through a total of 26’ of underground corrugated pipe. The outflow has pieces of foil to show air movement and by the end of summer the air coming back out of the ground is nearly 70f, having donated 35f+ in thermal energy underground. In the outflow pipe there is a 2cfm draw fan attached to a thermal switch. In winter, when the Greenhouse drops below 38f, it comes on. In The outflow air comes out at 65f+ early in winter, but as the winter wore on last year the thermal battery eventually fell to 50f output as it sucked in more and more cold air and used up it’s stored heat. The ground just got colder. But in any case, it certainly keeps the greenhouse from freezing except on the coldest nights of January and Feburary. On any late winter nights with temperatures below 20f, the thermal battery keeps needs some backup.
3 - Manual vents. We have a second roof window we leave open 24/7 April-September. Occasionally at other times. From June-August we pulled out a complete 3’ x 2’ roof panel on the opposite side from the window and replaced it with a screen. This, combined with opening the end door kept temperatures below 90f most of the time.
4 - A milk house electric box. In those coldest nights, when external temperature falls below 20f, the earth battery alone can not keep the plants from freezing, for these nights we run a milk-house electric heater on the coldest nights. It can be run manually, or attached to the same 38f thermal switch as the earth battery. Again we are grid-tied solar, so, we made the power here.
5 - Automated piston roof window. March-October. The Greenhouse makes MORE heat than we need to heat the house. Or use. A passive piston arm cracks open a roof window at around 75f and fully opens it by 90f. This vent replaces the “Side Door” we open into the house and vents the excess heat.
6 - Climbing Wysteria. We have started a Wysteria arbor in front of the greenhouse. In 2-3 years it will help shade the greenhouse in the summer and block wind in the winter
7 - Large heavy stone pots and massive planters full of dirt. It works. They get warm in the day, and then radiate heat at night, we have organized the greenhouse to optimize the solar collection of the darkest pots.
8 - Waste Dryer heat. I modified the dryer exhaust adding a diversion and cap system. From November-March-ish I put a cap on the usual dryer vent and divert the steamy heat into an underground pipe system. On one side of the greenhouse. We do our wash in the evening and but then wait and run the dryer as soon as we wake up. This otherwise “waste” hot and humid air raises the greenhous temp by 8-15f and creates condensation and rain in the process. It also has the very strange and cool effect of making the Greenhouse appear to be “smoking” as the steam fills the greenhouse and wisps out the cracks. This often saves having to turn on the box heater in the AM cold and just feels like a bit of a weird bonus in life to recycle your dryer heat. I mean...next level baby… You can see the blue tube in the first image.
Performance Notes/Impact of Greenhouse on CO2.
The prior owner of the house lived here over 50 years and kept meticulous records. From 1964 to 2014 they burned oil, initially in a forced air system. In 1992 they did a massive renovation. They changed forced air oil system into a heated water radiator system. In addition to the oil system they added two systems into the living room addition in 1992. A natural gas fireplace, sealed, with a thermal blower and an electric minisplit heater-cooler the mostly used as a cooling unit, but it can do both. The record shows they burned 480-630gallons of oil every winter. Average was apx. 550g. Each gallon of fuel oil burned creates 22.46 pounds of C02.
Using EPA calculators, the previous residents added apx. 618,750 pounds of C02 to the atmosphere via Fuel Oil. apx. 120,000 pounds via natural gas for cooking/heating and apx. 185,000 pounds for electrical generation for cooling/heating based on the C. PA energy mix.
Annualizing the records - this house 1964-2014 had an annual CO2 outflow of apx. 18,475 pounds per year.
We added grid-tied solar here in 2017. We generate apx 80% of our power on site. Our remaining 20% is purchased renewable via PA based wind and solar farms. Zero Carbon Dioxide, we also heavily use our minisplit as a heater for temperatures 40f-10f. The heat pump however gets really inneficient >10f, so then we run our natural gas fireplace and blower. We emitted apx 2,400 pounds of CO2 from natural gas systems last year. Most of that from our kitchen range.
Overall, thus far, we have apx. 8x reduction from the prior systems/owners in CO2 for this house, with the same number of folks living here.
Our first year, before we had the other systems in place. But burned 280 gallons of fuel oil with the pre-existing system. We burned only 150gallons total in the two years after that, replacing that thermal heat with grid-tied solar driving a heat pump. With the winter of 2020 adding the miniEarthship/Greenhouse to the grid tied solar and heat pumps we burned Zero Fuel oil. None. We don’t expect to burn any this winter. I am now figuring out how to evict the entire oil-water heating system which will mean tearing apart parts of the house, but so be it. Out with the Dark Past. A furnace guy I brought in to ask about how to get the oil tank out sail I would need to burn all the oil in the tank first. Pumping it out is harder and worse. Sigh. It is located in a room off the basement. It was put there when the house was built and getting it out will require dismantling either it, or a wall. Maybe that will be another diary.
Sometime in the next few weeks, as days get shorter and background temperature lower we will have to start using our heat pump, to augment the Greenhouse heat. But for several weeks, it has been heating the house nicely, and last year for the holidays we finished outfitting the planters and decorated it with lights and bowers. We plan to do that again this year. Though...it’s got a lot of things growing now.
When it’s very cold Dec-Feb, our heat pump will need bit of help from the gas blower insert in the living room.
I estimate our miniEarthship/Greenhouse build added 6800 pounds of CO2 to our atmosphere, but my math also indicates we have offset that with reduction in fossil fuel burning to date.
Here is the Annual C02 Output of this house by system use:
1964-2015 - 18,475 pounds per year (Oil+Gas Heat/Cooking, Coal/Nuclear Electric)
2016 — 15,500 pounds — our family using the same systems with lower thermostats
2017-2019 - 9,200 pounds per year (Less Oil+Gas Heat/Cooking + Grid Tied Solar+heatpump)
2020-2021 - 2,400 pounds per year (Thermal Solar/Greenhouse Gas Heat/Cooking, Grid Tied Solar+minisplit, No Oil.)
Experience/Feel of Greenhouse heating.
The layout of our house and the Experience/Feel of the Greenhouse heating is worth a note. It is a very passive heating and very quiet. Oddly, because the side door is open, I now associate increased outside noises - kids playing, the dogs, cars going by- normally summer sounds, with our greenhouse heating. The passageway from the Greenhouse stairs comes into the dining room-kitchen area, which gets very warm. From there the heat moves in three directions. Around a corner and up to the upper hallway and bedrooms via two hallways, across the dining room to the thermostat at my office door and across the kitchen to the thermostat on the far side of the living room. The Greenhouse heating makes the dining room/kitchen balmy. And all our thermostats are located at the furthest points AWAY from where the greenhouse is adding heat. But the “balmy” dining room got a couple of spot checks with a thermometer and showed 75f+ every time with greenhouse heat over the last two weeks. The house thermostats where we take data are in the next rooms, the living room usually adds 5-8 degrees of heat over 5-6 hours of greenhouse door opening in the winter, and then sheds that heat overnight. The upstairs hall and bedrooms tend to add 3-5 degrees during heating period and then sheds them at night. My office, the least impacted thermostat tends to add only 1-2 degrees from the greenhouse, and then sheds it again at night.
But boy do I love walking down our kitchen steps into the miniEarthship. It smells like heaven should, if there is a heaven. Warm air scented with tomatoes, lemon-flower, lavender and herbs. Yea. It really is that nice. Like I said, my wife just calls it “My Happy Place”.
Food Production - $240
We ordered a series of vertical growing towers and got the greenhouse mostly set up by October last year. Too late to really establish much food for winter 2020. But we got some greens. This year, we started our summer garden seeds in there. And of course our Greenhouse gave us all that lovely heat to get rid of our Oil Furnace. We also set up a small hydroponic greens area. It worked really well.
This past summer though we started prepping the greenhouse got all the planting going in September. It is now November. We have Celery, Peppers, Tomatoes, Lettuce, Beets, Artichokes, Carrots and about a dozen herbs established. We have a Meyer Lemon who has been cranking out blooms and lovely aromas for months - and has set lemons. Honestly I don’t care if it ever makes a lemon, I love the smell. My son, the tomato shark, patrols the greenhouse daily devouring them generally a day or two before they should be picked. But he got his wish. Tomatoes all year round. My wife calls the Greenhouse just “My Happy Place” and if the sun is out, she lives out there. And it heats the house on any moderate demand day, and adds measurable heat on any sunny day, even when it’s stupid cold outside. I continue to measure it’s performance, and plot ways to evict the now silent old oil system completely.
We spent $3663 cash, about 100 hours of planning and homework, and apx. 18 days of family joint labor to make our 1932 Central PA Home a Semi-Earthship, and had fun doing it. That in combination with heat pumps and grid tied solar I calculate this house now emits 8 tons less carbon dioxide per year from entering the atmosphere, and grows more food. And often pushes power to the grid for others to use. So there it is.
Somebody said - Be the change you want to see in the world. So yup. We be trying.
Will answer questions, if any, below.
EFMF.