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2 - HTM interior design photos of our zero-energy open floorplan earth home
click here for the main chapter of our free HTM Passive Solar Design eBook

HTM, sustainable, natural zero-energy passive solar housing in the 'earthship' earthome style. The basic design of our high thermal mass HTM™ sustainable housing, passive solar design is presented in the earth home style, but can be easily molded to fit your family's lifestyle and personal preferences, especially the exterior appearance. The open floorplans of our natural, sustainable, earthhome design can be boxed in later for storage, quiet areas, and sleeping spaces. Just keep in mind that as you section the home off, the need for supplemental heat and light is only going to increase. This is the basic nature of low-tech, mechanical-system-free passive solar architecture. We do our best to work with clients on all aspects of design: structural function, passive solar performance, privacy, flow, entertaining, lifestyle, family and caretaker unit considerations. Striking a balance between aesthetic desires and passive functionality is key with any sustainable natural housing earthhome design.

Simplicity of design is what allows an HTM to function sustainably

With full floor to ceiling glass, the view is endless and allows passive solar heat gain and natural light to penetrate deep into every room. The front South 'hallway' combines with the planterbed to create a very open, airy feeling throughout an HTM. As we will discuss in later chapters, you can box an HTM in to create smaller rooms, but this is easily and best done after the home is completed since interior partition walls are non-bearing. The main thing to keep in mind is the sustainable, energy independent nature of your HTM will be affected by cutting the home up into smaller boxed-in rooms. You are in-effect bit by bit turning an HTM into a conventional home. True, it will still function worlds better than any stick framed home, but it may need more supplemental energy and mechanical systems to heat and cool interior rooms that passive solar energy has been prevented from entering directly.

Looking east down the 75 foot long front hallway

As shown below, the living and kitchen areas are shared by the front entry room. Please note the lack of doorways and windows. This design feature is what makes a standard HTM so adaptable to underground home and fully bermed layouts. You really don't need doors and windows along any but the south wall in a heating climate. You are, of course, free to design your HTM with doors and windows on all four exterior walls, but by concentrating all of the glass and doors along the south wall, you simplify and speed construction, svaing money on building costs while maximizing thermal mass and functionality.

Open floor plan HTM living room and kitchen area 18 foot wide by 37 foot deep

Middle rooms are left open for use as living rooms and office areas or boxed-in for bedroom privacy. Utility, storage areas, and bathrooms are typically arranged along the rear North wall with clerestory windows or skylights supplying plenty of warm natural light. As you can see, wall treatments are more varied than just stucco, it is just that stucco and plasters are the natural choice with drystack block. Floor treatments are the most varied of all since just about anything goes in an HTM. Naturally, dark tile absorbs the most solar gain, but the immense amount of thermal mass allows you to choose carpet or hardwood floors for many areas of the home with little drop in overall performance.

Spare bedroom used as pool room alongside living room. Wood warms an otherwise stone dominated room

The master suite is typically an end room for the sake of privacy. Water tubes, glass block walls, drapes, or moveable partitions can be installed for additional privacy and a door can naturally be added to the hallway. These are all personal taste issues that are hashed out during the design stage as you take a closer look at lifestyle and family needs.

Master bedroom open to the hallway and planterbed before addition of curtains

Please note the nearly flat front roof section has a minimal 1/12 pitch to better catch snow for a 'thermal blanket' effect. In cold climates, snow on the roof acts as an extra layer of insulation for protection against the elements. This 1/12 pitch flat roof design has the additional benefit of preventing snow from falling off the roof and onto your glass and gutters. The perimeter of the roof is the first to begin melting when it warms up, so gutters are very easy to maintain without need for heat tape in most all climates. Irrigation re-use of the snow is another design consideration: as the snow slowly melts, it can be directed to interior planterbeds where the tomatoes are still blooming like crazy.

South-east front corner - note air intake and gutter irrigation pipes

Exposed purlin log vigas are a common south-western touch for HTMs. Design considerations include installing copper sheeting atop the exposed log vigas to ensure they do not rot and chinking cracks in the logs carefully to ensure home is kept as airtight as possible. Exterior fascia wall finish can be anything you want... vinyl or metal siding, logs, stone, brick, cedar shake, hardiboard, or whatever. Stucco coating is shown here and is standard practice for many clients due to its economy, inherent longevity, and maintenance-free convenience. Natural plasters can just as easily be used, but with a much larger eave overhang to better protect the plaster finish from rain damage.

North-east corner - note exposed purlins were copper sheeted atop

Shade cloth is being used below as an awning to block excess solar heat gain. Wing shading as shown here is an option, but it is more common to see a standard horizontal trellis with shade atop, like a pergola. Notice the line of shade as it extends a foot past the windows' bottom. Shade cloth is available from us in assorted colors and choice of shade protection factor to make custom designs for individual climates possible. Proper shade cloth layout is one of the keys to any workable, functionally passive sustainable design. In addition to blocking direct solar gain, shade cloth creates a micro climate around the perimeter of the home dramatically affecting the comfort level inside.

South-west front corner - note shade panel of 30% knit in spring and fall

The front hallway of an HTM doubles as planterbed access, really opening these rooms up! Light and airy is redefined with an HTM design. These homes have a feel and personality that is totally unlike a conventional stick-frame home. The combination of subtle radiant heating and cooling combines with the open floorplan to create a very livable, natural, healthy atmosphere.

Inside looking out the center patio door on south side

Indoor planterbeds get direct almost 90 degree penetration sunlight through angled glass at winter solstice. This ensures maximum solar heat gain and natural light when they are needed most right in the middle of a cold, dark winter. Sloped glazing may have an unconventional look about it, but it is the only way to sustainably grow crops AND heat a home. With a well-chosen building site, the glass can be hidden on the backside of the home in urban areas to mimic the look of a conventional house from the street. If you live in a hot climate, the need for sloped glass is likely not an issue and you can go with vertical glass to save money and present a more conventional look.

Planterbed as viewed from east end of hall - note fig tree that still grows 20 years later

Hanging plants are one option for room division and privacy. Drapes, sheers, shade cloth, water filled columns, glass block walls, and moveable partitions are some other answers besides building walls to box-in the rooms. Please note that interior doors and walls are easily added later, after you have had a chance to live in the home for a while and experience the difference that an HTM makes. Don't judge the open layout based upon living in conventional homes for your whole life. Clients are encouraged to live a floorplan for a while to get the feel of an HTM before building additional partition walls. The difference a drape 'wall' or movable partition can make is dramatic, without the permanence of a wall.

Bathroom outfitted with antique fixtures and plenty of wood and light from clerestory

HTMs provide endless possibilities for personalization of interior design. There are no limits to the variations, be it rustic with salvaged materials like you see here or something more modern. The key to passive solar function is keeping the floorplan as open as possible, but everybody has their own personal concept of their dream home, so alterations are made to the basic layout with understanding that every aesthetic change has a related functional effect. You take what free solar gain there is available in your area and supplement the rest, just like any other home. Form follows Function, with holistic design being critical in more sustainable zero-energy passive solar structures.

Rough sawn 9by12 timber beam used for bathroom door lintel goes with antique door and fixtures

Outside looking into bathroom - note how lintel softens the look of all that stone block

Passive Solar textbooks all seem to present a rather confusing 'shotgun effect' with a laundry list of options,
all based upon conventional residential stick-frame architectural models... but some do think outside the box.
Malcolm Wells' The Earth Sheltered House: an artist's sketchbook is rich in drawings and inspiration
Robert L. Roy's Cordwood Series includes SBC construction details and curved wall structures
Michael Reynold's Earthship Series for back-to-basics rammed earth how-to-do buildings
Daniel D. Chiras' The Natural House and The Solar House are both excellent textbooks
and with more focus on HTM construction... our free Passive Solar Design eBook
Unfortunately, we are not taking on any new HTM design consultation clients this year.
Hourly design services are not available currently and architect referrals are not given.
We have our HTM Home Tour DVD to offer... but it does not include any consultation time.

HTM Home Tour DVD

$10* with free USPS mailing
no international shipments

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HTM Home Tour DVD

First half hour walks you through our healthy, sustainable design, HTM passive solar, greenhouse style earthhome featured throughout this website. While not a How-To video, the second half does include some detailed Infiltrator® chamber leach field septic system installation footage. Plus, there's a segment on Sun-Mar® composting toilets.

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