Keya Lea

A Concrete Modern Passive Solar Home

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Why Concrete and Passive Solar Rock

Kitchen with stainless steel appliances complimented with the grey poured concrete floor and walls

Concrete poured walls and floors are found throughout the home. Concrete is also a finished material, that can potentially eliminate steps in the building process (no drywall).

In contrast, a traditionally stick frame built house that does not have thermal mass or windows facing the south, often relies on a heating system that heats the air within the house, while the house constantly looses heat.

This passive solar home works because the structure has a great amount of thermal mass, it therefore takes a longer amount of time to loose the heat that it has stored within the floor and walls as it radiates throughout the house.

Concrete as a building material has many cost effective advantages while being purposefully efficient.

Concrete is also a finished surface, thus it can have economical advantages and potentially can eliminate steps in the building process.

Because concrete can be sealed and stained, it can eliminate the need to hang drywall within the house.

Similarly, because it can be finished and sealed, there is no need to stucco or hang siding on the outside of the house, though if the owner desires it, it can be done.

This home has a flat roof, with a 3.5 inch drop within 16 feet. 

This project, which measures approximately 1,100 sq. feet, approximately $20,000 dollars were saved due to the elimination of these steps. About $350 dollars were spent on the stain, which simultaneously seals the wall.

The concrete walls are 10 feet tall, with a structure insulated panel system (SIPS) roof system laid on top. The roof has 3.5 inches of pitch from the north to south, within a span of 16 feet.

 

 

The SIPS Roof

The SIPS used are foam core panels, constructed out of polysterene (similar to the white insulation used in styrofoam cups) which is surrounded by Oriented Strand Board (OSB) a wood laminate material on both sides.

A Structured Insulated Panel System was used for the roof.

A Structure Insulated Panel System (SIPS) was used for the roof of the home.

SIPS have numerous advantages when building. They are structurally very strong while they are also lightweight.

SIPS provide very good insulation, and depending on its thickness, can have an R-value up to R-50. Because they are pre-assembled, there is a minimal amount of work in installation.

The SIPS that were used in this project were created and transported to the build site as 9 pieces that made the installation of the roof as simple as lifting the pieces onto the structure and nailing them together.

A single sheet of commercial grade EPDM (rubber membrane) covers the roof of the house.

Because the SIPS are are a flat surface and act as the roof, unlike traditional attic spaces, extra air space does not exist and there is no need to add any extra insulation, as the roof itself is the insulation. Ceiling drywall is also not needed and another step is saved and another potential cost is eliminated.

Covering the roof on the top outer surface is a piece of large EPDM (ethylene propylene diene Monomer) membrane. It comes with a 20 year guarantee and is the same waterproof roofing material used on large commercial projects. Potentially a rooftop garden can be utilized to help keep the house cool in the summer.
 

The Interior of the Building

The interior utilizes recycled materials and green finishes.

All the trim in the house is former barnwood.

The building utilizes color to emphasize warmth and lighting within the rooms.  For example, while most of the dwelling’s windows are to the south, the northern most room, the one that gets the least amount of light, feels sunny and warm.  It can be seen a picture shown previously in the article, showing the pitch in the roof.

The trim used throughout the house is former barn wood, while the doors and other materials were purchased from a local construction recycling company.

In order to create a sense of unity within the home’s design, the locks, doorhandles and knobs are all similar and were purchased directly from the manufacturer.  Since continuity in theme is important, the similar accessories were the most expensive aspect of the home.  It has created a sense of unity and a modern feel to the home.

Efficient design elements are found throughout the home.

Because they take less space, sliding pocket doors are used throughout the home.

Pocket doors, also known as sliding doors, are used in the house because they don’t take up any extra space as a swinging door does.

The laundry room is hidden behind a pocket door.  The sliding doors can quickly hide the stacking washer and dryer and a domestic chore from unannounced visitors.

There are strong fans installed in the bathrooms.  They are efficient, quiet, and an integral part of the summer cooling system. In the evening, when the windows are opened to the cooler night air, they draw heat from throughout the house and send it outside, while cooler air is drawn in.

 

Radiant Heat – Hot Water System

The water tank for the house is 9 feet tall and is surrounded by a spray foam insulation.

While the home has been designed as a passive solar home, the heating and cooling systems have been integrated with active solar elements.

The home has in-floor radiant heat pipes throughout the concrete floors.

In the utility room, a large 9.5 foot water heater (picture shown in the gallery above) is actually comprised of two internal tanks with two different glycol systems: one for hot domestic water use, and one for heating the house.

A water glycol blend from the tank is sent through solar thermal panels on the roof. They collect heat from the sun throughout the day as the glycol system circulates through the large storage tank, transfering its heat to the water through a water coil.  The glycol in the tubes never mixes with the water.  Both the glycol and the water are in separate closed loop systems.

In case there are a few cloudy days, there is also a flash water heater that is used for backup.

With its thick, tall, dense wall, the home feels safe and secure.  The use of concrete on the outside and inside of the home works within the four season, yet mild and sunny climate of Colorado.

 

Designer / Builder – Sven Krebs

Time to Build – 2.5 years

Square Footage – 1100 feet

Cost – 100 per square foot on materials, doing own work

 

 

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24 Responses to A Concrete Modern Passive Solar Home

  1. barb krebs July 24, 2011 at 1:01 pm

    Keya–What a great article! I especially enjoyed all the photos. They really help illustrate what you are saying and they make the house look good. Thanks a lot.

  2. Ana July 25, 2011 at 10:16 am

    What did you use to make concrete floor in living rooms to look shiny? Great home!!!

  3. Keya Lea July 25, 2011 at 12:27 pm

    I asked the builder and he said that a combination of things made the concrete floor look shiny and so striking. When the floor was poured, it was hand troweled to give it that ultra smooth finish. After it dried, they used a high gloss sealer to finish and protect the floor. It was also cleaned just prior to the pictures being taken.

    Thanks for your comments!

  4. Matthew August 2, 2011 at 1:38 pm

    I want this house!

  5. Keya Lea August 2, 2011 at 7:23 pm

    Matthew – the builder would be happy to build you one.

  6. Kuhn Oberholtzer August 24, 2011 at 5:00 am

    Keya,

    I Really love the use of concrete in the construction, it’s such an underrated material.

    Where can I get more info on the water/glycol system you guys used for the solar heating system?

  7. Keya Lea August 24, 2011 at 10:53 pm

    Kuhn,
    Here is a link to another solar hot water heating / glycol system that explains this type of system in better detail:
    http://greenpassivesolar.com/2011/01/active-solar-thin-film-evacuated-tubes

    The link is to an article on a grid-tied house that integrates both solar photovoltaic film and solar evacuated tubes – that use glycol to tranport the solar heat into a water tank / heat exchanger. It is similar to the system that is used in the concrete house, but goes more indepth in the explanation of how the glycol and heat exchange takes place within the water tank.

  8. Suzanne January 16, 2013 at 1:25 pm

    Now that you have lived in the home a few years I’m wondering how often the radiant heat floors are used? I hope to build a passive solar home this summer. I wanted radiant heat tubing put in the concrete floors, but have been reading that radiant heat can over heat the house. That it is better to use that money on other things such as more insulation, etc. How would you respond to that?

  9. Keya Lea January 17, 2013 at 12:02 pm

    Suzanne,

    I emailed the owner of this house and asked him to follow up with your question. In the meantime, here are two houses that have radiant in-floor heat.

    They both are located in cold, mountain climates, in sunny Colorado. This one is grid tied – http://greenpassivesolar.com/2011/01/net-zero-pv-log-home/. It uses solar thermal to both heat hot water for domestic use and for heating the home. In the case that the system gets too hot, for example, in the summertime, the heat sink (heat dump) was plumbed to the garage and not to the living areas. This might be something to consider.

    This house was built really efficiently (double studded wall, double roof, triple gusseted windows, etc.) and while it was plumbed for in-floor radiant heat, is not used because the house doesn’t need the extra heat. This one is off-grid. http://greenpassivesolar.com/2012/03/optimally-efficient-off-grid-passive-active-solar-home/

    Best of luck to you and your build! Keep in touch.

  10. Sven January 24, 2013 at 9:15 am

    Susanne, the cost of installing tubing in the floor is minimal and gives you an easy and flexible way to control it’s temperature. It’s also a simple way to prove a back-up heating source to satisfy a mortgage lender’s requirements if you (or a future buyer) need financing.

  11. Roger June 4, 2013 at 2:31 am

    Does Sven sell plans of this great house?

  12. Keya Lea June 5, 2013 at 11:20 am

    I think so. I asked him to get back to you, but was not sure if he emailed you directly, or would post here… Let me know if he doesn’t get back to you.

  13. Carl Simone June 19, 2015 at 5:28 am

    This is a great house design! I lost my house to a fire last January and I decided to rebuild with concrete. I’ve been looking all over the internet for house plans that don’t cost an arm and a leg and I certainly can’t afford an architect. Would Sven be willing to sell a copy of his blueprints?

  14. Keya Lea June 21, 2015 at 8:16 am

    Sorry to hear that you lost your home to fire. I’m trying to get in touch with Sven. I think that he would be able to sell a copy of the blueprints. Hopefully he’ll be able to get in touch with you soon!

  15. Troy Conner April 5, 2016 at 3:36 pm

    Keya,
    Thanks for this article. My wife and I are trying to build a concrete home in Texas but we are having difficulty with design work and finding builders competent for the task. We are reaching out to others who might be able/willing to help get this project started. I would love to contact the owner and/or builder for some much need advice.
    Kind regards from Quihi, TX,
    Troy and Tricia Conner

  16. Keya Lea April 10, 2016 at 11:42 am

    Hi Troy and Tricia,

    I talked to the builder and he’s open to talking. I’ll email you info.

  17. Marcel April 25, 2016 at 1:05 pm

    Hi,

    Thank you, this is awesome. Will you forward my email to Sven. I would appreciate more info on the process.

  18. Keya Lea May 8, 2016 at 9:56 am

    Sure, I’ve forward it to him. He does consultations as he did a lot of problem-solving when building this house.

  19. T June 19, 2016 at 2:47 pm

    This is an awesome house. What is the approximate cost to build something similar?

  20. Keya Lea June 25, 2016 at 5:50 pm

    I think it was around $150,000.

  21. Virginia July 26, 2017 at 9:20 pm

    Hi, I was looking for passive solar plans, and I usually find huge houses. This is the best so far! I couldn’t find how many bedrooms are. Can’t see the floorplan well. And my second question is, as I live in South America, wich sun goes to the lateral window on the north side (morning or afternoon?) Thank you so much for this post!

  22. Amanda August 28, 2017 at 5:42 pm

    How do we find house plans & a builder for a home like this in upstate New York? Any information is *greatly* appreciated!

  23. Keya Lea August 31, 2017 at 3:45 pm

    You might want to try a google* (or any other search engine) for “concrete home builders upstate new york”. That might be the most efficient way, beside word-of-mouth and asking around your local area. My apologies, I don’t know any upstate New York concrete home builders.

    That home was built for the specific area, so it might be worth asking around your local area for someone who knows local climate conditions. 🙂

  24. Keya Lea August 31, 2017 at 11:02 pm

    This is a two bedroom, one and a half bathroom house.

    You’re welcome! If living in South America, because you are in the southern hemisphere, in order to receive full sun, the windows should face the north, instead of the south. As for specificity on solar movement in lateral windows, that’s specific to location on the globe, and depends upon both the window size and location, as well as the size of the overhang.

    Here are some links to homes built in the southern hemisphere, specifically in New Zealand.

    New Zealand homes

    Best of luck!

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