sustain

Sustainability

ENERGY

How does it perform in winter?

Our models are unique in that they are designed for energy efficient performance in the dead of the Canadian Winter – unlike any other RV or trailer on the market that suffer from drafts and poor levels of insulation due to inadequate wall, roof and floor detailing. This is because most RV’s are designed for seasonal occupancy only, whereas Sustain’s units are designed for comfortable, year-round living.

The walls, floors and roof offer R38, with minimal thermal-bridging (cold spots due to structure) almost eliminated. This gives us at once a robust wall, roof and floor construction that also resists condensation on the structure’s cold-spots that can otherwise lead to structural damage.

Windows are high-performance (R3.5), low-conductivity fibreglass with low-e argon inserts. All of the plumbing, tanks and systems onboard are contained within the insulated shell of the building, which means the systems will not freeze (provided the building is occupied, or a baseline heating level is maintained). Since our units have a small volume, they will rapidly warm up to a comfortable temperature, making weekend winter visits a pleasant experience! This extreme performance means that Sustain units will also be easy to cool in the Summer (see passive cooling section). ↑

Can I add a wood stove to heat it?

We have designed a place for a woodstove in our more recent models.

For US-Bound miniHomes, especially units headed for the Pacific Northwest, we strongly recommend the Platinum Cat – a radiant catalytic furnace that features extremely low electrical energy consumption, miserly propane consumption, and a dedicated supply of ‘combustion’ air. This will help keep ‘Wet-Coast-Chill’ at bay, while prolonging battery storage in the sun-less weeks and months of the Pacific Northwest’s Winter. ↑

How well does the Ventilation System perform?

Our units are designed with a passive cooling system that works by natural convective and wind-driven ventilation. Keeping building materials cool and thermal transmission low is acheived by ventilating the exterior cladding is by using a 1/4″ unobstructed airspace. Venting/cooling the unit at night, and closing all windows and blinds in the morning also will help the unit stay much drier and cooler during the warmer months. Though these strategies alone won’t work in every climate they reduce the load to minimize the demand on an HVAC system.

Heat Recovery Ventilation (HRV) systems are used to introduce fresh air to the units. This ensures a steady stream of fresh air through a dedicated port, that is evenly distributed throughout the home. Of course – one is always free to open windows at any time. Stale, humid air is extracted from the bathroom and kitchen (instead of exhaust fans, which waste thermal energy) – and is used to warm the incoming cold air – which gives an energy savings of approx. 70% in heating energy. In Summertime, HRV’s can assist with dehumidification, but the extent this is a factor of exterior humidity levels. Additional dehumidification may be required. We cannot recommend Air Conditioning for off-grid applications, the electrical power demand is too great. We can provide any of the 4 systems listed below for different conditions: Economical Heat Recovery High Performance Heat Recovery HEPA Air Filtration with Heat Recovery (Higher Electrical Load) Moisture Control and Dehumidification

While a generator for Air Conditioning can be added, (which is noisy and polluting -except the Whispergen system, which comes at a heavy cost premium), we’d suggest you try a season without AC.  In humid climates where air-conditioning is the norm, our units’ building envelope will resist reverse condensation in the building envelope. The wall cavity is effectively air sealed from both directions, using a combination of gasketed, vapour impermeable wall-boards, to resist ‘normal’ vapour migration (for cold weather climates) and a taped, extruded polystyrene cladding on the exterior to prevent ‘reverse’ vapour migration towards the cool interior regions of the wall. ↑

MOLD + MAINTENANCE

How is mold prevented?

Mold requires 3 conditions to grow; moisture, heat and air. When one of the three conditions is eliminated, mold cannot grow. In response to this pervasive issue in reserve housing, our units are designed to breathe and shed moisture so as to not allow mold and decay in the first place. We use foam insulation because it not only seals cracks to avoid heat loss but also prevents the heavy build up of moisture which substantially lowers mold and mildew problems. We use rainscreen cladding because it provides predictable, unobstructed path drainage for liquid moisture to drain from a high point of the wall (where it enters) to a low point of the wall (where it exits) to prevent absorption and consequential rot, mold, and structural degradation. ↑

How do I maintain my unit?

Well, that’s just the point – you don’t really need to! Every unit’s owner manual contains a complete specification and manufacturer’s instructions for the care (as in washing) of all of the materials and assemblies used in our units. This website will also mirror all content in the Owner’s Manual, and you can always ask us via email: info@sustain.ca. ↑

WATER

What are the Water Requirements?

You will need a reliable water potable (drinking/cooking/bathing) supply. This can come from a well, or a lake-pump, or even an advanced rainwatwer harvesting and filtration system – but these systems are not part of the units themselves. ↑

What about Wastewater/Septic treatment systems?

Wastewater must be pumped out or treated per municipal requirements. An external (Clivus/Sunmar) – or – internal composting toilet (Sunmar) are available aftermarket options, both of which reduce and can even eliminate the septic load – but a greywater system is still required.

Constructed wetlands is a water treatment system that is being considered for a new park development in Brighton Ontario. Wetland septic systems are a simple and effective method to treat domestic, agricultural, industrial and mining wastewater. These wetlands are lined with clay to prevent leaks and are then filled with rock, gravel, sand, and soil. Aquatic vegetation is planted in order to provide habitat for the microrganisms that actually treat the wastewater. Wastewater from the home flows through the septic tank, where the soilds are removed, and into the wetland where it is distributed evenly.

Using a composting toilet with our units can transform human waste into benign humus (not hummus) – reducing the wastewater load significantly, as 95% of what we put into a toilet is moisture. Since the primary goal of most composting toilets is evaporation of this 95%, the treatment of the remaining 5% is easily handled by aerobic bacteria and microorganisms. Modern composting toilets do not smell, there is a constant, slight vacuum pulling air into the toilet lid and up and out an exhaust stack (part of the evaporation process).

Wastewater from the tub/shower and sinks – Greywater – exit the miniHome from a dedicated plumbing line that is separate from the Septic /Blackwater output, and can subsequently be treated with an aftermarket Greywater System*. A Greywater Treatment System is different from a Septic System in that it can consist of a series filters and raised-bed planters that cascade from one to another, absorbing nutrients and cleaning the water as they go. These systems often do not require the extensive land disturbance and expense of a conventional tank, cesspit and weeping bed system, and have received municipal approval in hundreds of cottage installations ↑

What other water systems can be implemented to make my unit more sustainable?

In our prototyped models, we had standard RV-style tanks for freshwater and wastewater. The tanks gave us around 20 days of storage before we needed to refill the freshwater and empty the wastewater. Given that most people are using our units in a full-time capacity, the source of water and wastewater processing is something that needs to be dealt with on-site. Most municipalities have guidelines governing these systems, and they can vary from state to state and province to province. Please contact us for more detailed information on Freshwater, Greywater, Rainwater, Septic and Composting systems as we have partnered with several engineers and manufacturers that we can refer you to design and deliver these systems if requested.

Rainwater collection for irrigation from our two, centrally located downspouts – is an easy addition of a tank and filter under the entry deck.

>*Our preferred Greywater treatment solution partner: Ecowerks
Clivus Multrum Toilets (exterior to miniHome option) website is here, and are recommended for year-round usage with more then 4 persons.
Sunmar Composting Toilets are located here. These can be located inside the miniHome and are appropriate for 2 person, fulltime usage. ↑

MATERIALS + RESOURCES

What do you mean by 100% green materials?

Even when the miniHome was only 1-day old out of the factory, it didn’t have any of the noxious off-gassing and poor indoor air quality that plagues most vehicles, trailers, houses and manufactured products. That’s because we set out a very exclusive set of criteria for our manufacturers, which demands:

No vinyl
No formaldehyde
No toxic adhesives or finishes
All water-based, or plant oil-based finishes
No CFC’s
All woods to be certified from sustainable sources whenever possible (FSC certification)
High natural ventilation rate (windows open)
Constant fresh air supply (windows closed) via heat-recovery-ventilator
Durability and Low-Maintenance

This ensured both high indoor air quality with the pleasant aromas of unfinished cedar and pine (which are given a light coating of water-based urethane to give an easy-to-clean, satin finish). ↑

Are these materials durable?

We consider durability an important measure of sustainability. Wherever possible, we have opted for homogenous materials, with little or no requirement for maintenance – in the form of painting, or re-finishing. We have also detailed materials to be mechanically fastened so that they can be easily repaired or replaced, and that are designed to breathe and shed moisture so as to not allow decay in the first place. Some examples are;

Western Red Cedar has astonishing resistance to mold and rot, and if allowed to breathe properly (no oil or coatings applied) it holds up incredibly well in saunas and bathrooms, and can be scrubbed with plain water to clean. We have over 16 years of positive experience with this material applied to shower and sauna walls.

The Rainscreen Cladding materials do not require painting, are rot-proof, UV-stable, and can be washed with a pressure sprayer. We have also ensured that the way the building is put together prevents moisture from collecting in undesirable areas (using Typar and Ice & Water Shield where required).

The natural rubber flooring resists spills, and is easily cleaned, while the optional hevea hardwood flooring is pre-treated with eco-oil, and does not require any form of waxing. A light retreatment oil can be applied after 5 years.

Our framed walls and SIPs floors and roofs are completely gasketed and airtight and do not allow the exfiltration or infiltration of airborne moisture, plus there is no organic material (aka. food) for mold to take root in or on.

All materials are detailed with mechanical fasteners such that replacement and/or repair does not require destructive removal, ultimately allowing recycling and/or repurposing.

SITE + LANDSCAPING

Does it need a foundation?

‘Skirting’ – that we provide and install – hides the wheels (basically forming a kind of crawlspace under the unit), and the hitch is removable – so that the miniHome looks just like site-built architecture. This provides tremendous flexibility, should you move or sell your property, it also expands your home resale market to the entire continent. The miniHome gives all of the benefits of mobility, with all the style of a modern condo. The miniHome line of units do not require permanent foundation, however, some states will require the unit be placed on a foundation. A simple sonotube-type concrete post foundation, concrete pad or even simple leveling and blocking will suffice in most jurisdictions. We are currently looking into other options for building on regions of permafrost in the Far North. ↑

What about Landscaping?

Our designs also works with natural assets and conditions of the site and require no excavation and minimal site work. Thus, the existing vegetation can be preserved to ensure local, low maintenance landscaping at no extra cost. Using the indigenous vegetation also reduces run off and irrigation demands outside. ↑

RENEWABLE ENERGY + GOING OFF GRID

What do you mean by ‘Off-Grid’?

Even off-grid buildings require food (fuel) air and water just as living organisms do. Off-grid typically means not connected to any form of municipal infrastructure – which usually refers to electrical and gas servicing.  Our units can be configured to not require gas or hydro hookups, but they do need a water supply and a wastewater treatment system (Greywater and/or Septic)*.

The miniHome SOLO and DUO produced all the energy required for their onboard electrical loads by solar panels (located on a pivoting aluminum canopy over the front door) and an optional 400Watt wind turbine can help with more intense usage (that mounts on a 16′ mast mounted to the loft wall, or can be sited on a taller mast – not provided – for optimal performance). We also have an onboard propane system for space heating, hot water, cooking and refrigeration. The 12WIDE models are designed to work with renewable energy systems – but we recommend these somewhat larger systems be installed and serviced by local renewable contractors to best take advantage of regional incentive and rebate programs. ↑

How can all of my energy needs be met by a couple of solar panels?

The easiest way to meet all of your energy needs with a small, simple system is to reduce loads as much as possible. Since our units are small and well insulated and feature super-efficient appliances, it is easy to heat and light with a tiny fraction of the energy required in a regular house. All lights, pumps and fans in our units are the most efficient models we could source and anything you plug into a wall-outlet is powered by a 2kW inverter. Heavy thermal loads such as the refrigerator, furnace, hot water and oven/range are powered by propane – which is over 95% efficient as a primary energy. ↑

Why don’t the 12WIDE units have solar or composting toilet built in?

We aren’t selling renewable systems with the 12’s, but that doesn’t mean we haven’t planned for their integration*. (*We have designed all 12VDC Lighting and refrigeration (Sunfrost), and DHW and Space Heating is by propane) There are three reasons for this:

1. Different Use Patterns require different system capacity design

2. Local Incentive Programs may require local contractor installation

3. Local contractors provide service and warranty when required

Regarding #3 – This has to do with how different utilities buy power back – typically, one needs to purchase (and install) in-state to take advantage of incentive programs, such as the Standard Offer Program in Ontario and CEC wheeling setup in California – or the . We can size the systems for you (at a nominal fee), or give you the electrical load of the various units, and you can add the systems yourself and take advantage of any existing incentive programs.

We can sell the units with composting toilets, etc. but it is often cheaper to get these locally, and have them installed according to municipal codes as these vary from province to province and state to state. What we have packaged is a very high quality, well insulated unit, with extremely efficient appliances and fixtures, such that any renewable system added to power the load, is just a fraction of that of a conventional house.

For an idea on pricing for some of these items, check out: http://realgoods.com

The solar system typically should be sized for a daily usage of 800W to 1.2kW – this sizing will power the refrigerator, but not the HRV (Winter only, or for Summer dehumidification/cooling). The fridge onboard is a Sunfrost RF16, and the HRV (Heat Recovery Ventilator) requires 100+ Watts when in operation these two items are the single largest electrical loads. ↑

Can I add a generator to augment the system?

Yes, but it shouldn’t be the first thing to consider, as a little practice and experience living off-grid – with our system design – can convince one that it really isn’t necessary. We set out to engineer and design a home that could run on as little power as possible, and then power this little bit with energy from the the sun and wind. We went to great lengths to design the appliances and systems onboard to be as silent and trouble-free as possible – to complement the energy systems (for example, the refrigerator is completely silent, a welcome feature in a small space). We have also tested the system in as designed and have found that it performs as expected. That being said, if you plan to run a table saw, an air-conditioner (see section on passive cooling), or other heavy appliances, any genset will easily tie into our units’ modular electrical system. We have several recommended accessory generators that can be run on biofuels, and the Whispergen central plant, that provides silent power, heating and hot water from a single, compact unit. To learn more click here: Whispergen (PDF). SDS Recommends the following aftermarket generator packages:

A good, quiet, air-cooled genset is the Honda 1000iC (for light battery charging)
A good, quiet, air-cooled genset is the Honda 3000iCA (for heavier loads)
A good, powerful, water-cooled, 2-stroke diesel (yes, it can run on biodiesel) genset is The BDBC by Ample Power Systems of Seattle, Washington (as this one is water-cooled, you can also use it to provide Hot Water and Space Heating)
The Whispergen DC Unit, by Whispertech, of New Zealand – The undisputed ‘King of Quiet’ ↑