Why a solar house for Meldrum Ridge Mini Ranch?
Work in progress, last updated January 12, 2018. Questions or comments may be addressed to MeldrumRidge@gmail.com. Expect up to 7 days to reply.
With her permission we are directly quoting, or in some cases interpreting from personal laymen perspective, the architect Debra Rucker Coleman and her book The Sun-Inspired house. We are also including results of online research from numerous other sources
Question: Where are you in the project?
We have the deed to the lot and a prepping for the clearing.
Question: Why solar and specifically direct gain solar?
Answer #1 Comfort and Psychological benefits
For us #1 is the psychological benefit:
“The closer we stay to nature, the more healthy we become both physically and mentally. A light breeze can be refreshing. It can be just as stimulating to feel household light and temperatures change daily as it can be to watch the sky change with the seasons. Both heat and light come from the sun and should stimulate the senses in order for people to stay happy inside and outside the home.
• Sunny interiors: Patterns of sunlight and shadow change throughout the day and vary with the seasons. This brings life and variety to the spaces inside a house. Sunlight also brings life to people as it alerts the senses and awakens the soul. Natural light also makes interior spaces feel larger.
• Closer to nature: Being aware of one’s natural surroundings can have psychological beneffits — seeing the leaves blow in the wind, feeling the breeze across the skin, or absorbing the warmth of the sun’s rays while nestled in a window seat.” The Sun-Inspired House.
In the 4th century Socrates said: "Do you admit that any one purposing to build a perfect house will plan to make it at once as pleasant and as useful to live in as possible?" and that point being admitted, the next question would be: "It is pleasant to have one's house cool in summer and warm in winter, is it not?" and this proposition also having obtained assent, "Now, supposing a house to have a southern aspect, sunshine during winter will steal in under the verandah, but in summer, when the sun traverses a path right over our heads, the roof will afford an agreeable shade, will it not?
Our conclusion: As the breeze flows up the ridge from the lake, wouldn't it be totally inspiring to do yoga sun-salutes in your tower room of windows as the sun comes up in the morning or on a west porch as the sun sets in the evening?
Answer #2 Direct gain solar takes advantage of the natural surroundings and site orientation
Two facts and specific traits in the design we chose
• In winter, the sun rises in the southeast, remains low in the southern sky, and sets in the southwest. Windows on the south allow the low winter sun to enter and warm the home.
• During summer months, the sun rises in the northeast, climbs high in the southern sky, and sets in the northwest. Overhangs protect south windows from the high summer sun.
Architect Debra Coleman's Sun-Inspired homes utilize the fixed components of windows, overhangs, insulation, and thermal mass to control the sun’s heat and light that enters the house without active measures by people or machines. Used together, they create a passive system used for both heating and cooling. A “passive” system takes advantage of naturally occurring energy in its surroundings to serve a purpose without the aid of auxiliary mechanical equipment. These systems consume no threatened resources and produce no waste. The ample energy of the sun can be easily manipulated by passive systems to make homes more comfortable and energy-efficient.
And in this 1999 NC Solar Center article:
"Direct gain is the simplest approach and usually the most economical to build. With this system, sunlight enters the house through large areas of south-facing glass. It heats the floor and walls directly.
Energy from the mass in floors and walls is released to the living space when the inside air temperature is lower than that of the mass.
Advantages of the Direct Gain System:
• It is comparatively low in cost to build, since no special room has to be added. The floor, walls, or even an inside- wall fireplace can serve as the storage mass. The solar elements are incorporated into the living space.
• It provides direct heating. There is no need to transfer energy from one area to another.
• South-facing windows provide natural daylight and outdoor views.
• The number and size of south-facing windows can be adjusted to match the space you have for thermal mass. "
Another article published in 2011 in BuildingGreen.com emphasizes the other elements of heat storage:
"Direct-gain passive solar systems rely on south-facing windows to bring solar energy directly into a house. That sunlight is absorbed by materials in the house (the floor, walls, furniture, etc.), which warm up, store some of that heat, and re-radiate it back into the room, warming the space.
One way of looking at this is that the house itself serves as the solar collector and heat-storage system. There are no fans or pumps to move heated air or water around. The systems are silent, trouble-free, and easy to maintain--by washing windows and, in some cases, opening and closing window blinds to adjust incoming solar gain. The thermal storage function is most effective with high-mass materials, such as tile or concrete floors, fireplaces with brick or stone facings, and tinted plaster walls. These materials keep the space from getting too hot during the day, and they continue radiating warmth into the living space in the evening."
Question: How do actually achieve the inside comfort?
A natural, i.e. direct gain, solar designed and built house requires well insulated, well sealed construction which unlike many houses, will not have the energy escapes nor airflows from leaks. Therefore, it takes active participants to best establish the desired comfort levels for temperature and airflow. Which windows to have open when, the proper use of ceiling fans and how to make sure the inside air is properly changed out with fresh air. The interior design also must take into consideration the balance of thermal mass to solar gain.
At times such as the hottest part of the summer or coldest part of the winter, this will be achieved with the addition of an HVAC unit with Energy Recovery Ventilation (ERV), sized specifically for this house.
Question: Isn’t green building expensive to build?
It depends on many factors and there are a lot of decision points and tradeoff’s. Here are some possible answers.
Answer #1 Passive solar as low-cost green feature
How you choose the site and take advantage of natural features is critical. Choosing a natural E-W ridgeline makes other decisions easier.
The points mentioned previously can be cost effective if you have the algorithms and the experience to place the correct amount (%) of south windows and then the appropriate amount of thermal mass for the specific region and climate of the building site. Our design should do just fine with 8% or less of southern windows and the thermal mass all afforded by the structure itself.
My research has shown that there are lots of ways to use the whole house as a thermal mass and adjust the balance even after moving in by adding window treatments, phase-changing materials such as ThermalCore drywall, thermal mass objects such as sculpture pedestals and so on. Even adding features that take advanatage of Phase Changing Building Materials (PCBM)- Natural Heat Storage in Buildings, as discussed in this recent article in Ecohome . Phase Change Furniture is also being designed and tested. We hope to add this at various stages to manage the temperature.
Strategic Solutions: construction PCBM additions to walls, roof or floors.
Tactical Solutions: post occupancy. Employment of energy management products for comfort, balance, room purpose variations.
What we intend to employ and test using wifi thermometers, humidity monitors, energy bills
• Wall hangings on verticals to peaks of the sloped ceiling
• Granite kitchen countertop. Possible built in PCBM panel under island.
• Builtin eating area in SW corner with panels and veneer top table top
• PCBM filled hollow core doors
• Wall behind fireplace surround
• Sculpture pedestals made with PCBM panels
• Gallery wrapped paintings to have the PCBM inserts.
• Carolina Closets Plus custom closets, home office and unique spaces builtins to have PCBM backs.
• Enclosed porch with Eze-Breeze vinyl windows to have wall hanging (idea from Southport resident who would also be a tester.)
All of the active solar features, such as solar panels could be added later.
Answer #2 Smaller is less expensive to build and operate
Answer #3 Simpler is less expensive to construct
Sun Plans, Inc French Cowgirl series are "simple" to build from their Plan Complexity categories of Simple, Average, Complex. Check out the list of Sun Plans as they relate to complexity.
Answer #4 Attention to insulation and sealing adds most of the costs
Direct quote from Sunplans.com/learn/costs "It’s hard to isolate just the passive solar components since it is not recommended to add passive solar until a home’s “envelope” – the surfaces (walls, roofs, floors) that surround the living spaces – is properly insulated and sealed. A good “container” is needed to hold the free energy. Holes in a bucket would be fixed before adding water. To create a good envelope, it takes a little extra time and typically a little more money from the home owner to install the insulation carefully and to caulk, seal and pay attention to air leaks. And as long as the insulated cavities are being sealed up “for good,” if there is room without compressing it, why not put a little extra insulation in too?"
Answer #5 Shading in the Summer & Max sun in the Winter is critical
Sounds simple enough and it is if you build the roofline overhang with the correct calculations. A great one I found was an online calcualtor shows you the shading you will have for any day / time during the year. Learn more
Answer # 6 Upgrade or add elements later for tight budgets
Builtins including custom closets, home office, laundry: No matter how you imagine and plan to live in a new house, you don't know what it is really like until you actually live there for a while. To save on initial costs our plan is to forgo the high costs of custom builtins until we understand what we need. Then being avid DIYers, we do it ourselves or bring in experts like Carolina Closets Plus who has over 30 years experience, continuous 5 star reviews and an all inhouse operation for CAD design, direct to their own manufacturing equipment and their own installation team. They also have the best DIY package around (ClosetDIY.com). Advantage of CCP operation: you have a shelf that is 1/4 inch off at installation, they could replace it that same day.
Answer #7 Lower cost HVAC system
The direct gain solar design of the house by Sun Plans substantially lowers the need for supplementary systems. From Sun Plans website: "The additional energy required to heat the home can be greatly reduced with the combination of increased insulation, air sealing and a proper design of whatever type of supplementary or auxiliary system is used. Even the best-performing passive solar homes will still need some form of heating from electricity, gas or wood in addition to the sun, but much less of it. Heating systems can be downsized.
Also, there are Duke Energy incentives for builders of energy efficient homes with rebates up to $9000. More detailed information can be found at the RNC builder program . From the NC Clean Energy Technology website "Duke Progress Energy's residential new construction program provides cash incentives to builders and developers who build new energy-efficient homes and multi-family residences that meet program requirements specified on the program web site. Equipment rebates are available for heat pump water heaters and high efficiency HVAC equipment. Separately, builders can receive rebates for new homes built to meet or exceed the High Efficiency Residential Option (HERO) code, which is an optional part of North Carolina's 2012 Energy Conservation Code. "
To maximize energy recovery and continual fresh air throughout the house, we will use an ERV (Energy Recovery Ventilator) which quite simply moves outside stale, dirty air out from typically dirtier air areas while bringing in fresh outside air to areas such as bedrooms where you want freshest, cleanest air.
As it does so, the two flows of air pass through a heat exchanger and many units also preserve 90% of the heat in the winter and prevent 90% of the heat coming in in the summer. They have a similar effect with humidity taking a load off the air conditioning in the summer. The ERV can be integral to the HVAC system and is the current plan for Meldrum Ridge House.
The HERO code is achieved through quality of build, exacting insulation and a blower door test. The insulation inspection and blower door testing is being done by Southern Energy Management of Morrisville.
Answer #8 Planning & working closely with the builder, the NC Clean Tech Center, a RESNet certified consultant
Checklist for looking for a builder
As mentioned previously Duke Energy has significant incentives under their HERO program. (High Efficiency Residential Option)
The RESNET (Residential Energy Services Network) is a national network of raters and consultants who can check the home at various stages in construction and certify that the home meets the Duke Progress Energy HERO code or the nationa EnergyStar rating .
Answer #9 Cost-effectiveness
We have dedicated quite a bit of time in evaluating options to achieve cost effectiveness. For example siding and roof, we learned the tradeoffs in maintenance, fire resistance, ease & cost of repair from severe storms or wind damage and cost of various options. Vinyl, unfinished cement board & panels, pre-finished cement board, wood, stucco each have tradeoffs, but each industry is continually developing new products that can make their product more cost effective.
We think the Duke Energy builder incentives mentioned previously will also significantly offset any of the higher costs of making the home more energy efficient.
Question: What are the actual short tem and long term $$$ benefits?
Answer #1 Duke Energy Incentives
Duke Energy Incentives for Home Owners A three year Heating and Cooling Energy Usage Limited Guarantee
Duke Energy Incentives for Home Builders Discussed previously.