FREQUENTLY ASKED QUESTIONS

 BTF Net Zero Homes are:

→   Designed for Contractors: Easy to build  

→   Same cost to build: Comparable $/SF as typical construction  

→    Architecture, HVAC, Energy Analysis & Solar PV within one drawing package  

→    BTF plans are preferred by both contractors experienced with, as well as for those new to, Net Zero.

→    Ready for construction, on nearly any site in 35 States  

→    Save you time. BTF Net Zero plans include Architectural, HVAC, Energy Analysis & Solar PV coordinated & within one drawing package. We are one of the first in the country to be successfully offering this solution. And this solution means, no longer do you need to hire a mechanical design firm & architect, for months of site specific net zero design. We've done the engineering for you. 

Net Zero homes are simply designed to create more electricity than they use throughout a year. 

Typically Net Zero homes use solar PV arrays to generate electricity. 

Although there are some Net Zero  homes that may use other renewable power generation sources, such as wind or hydro-power. These systems are less common for their complicated design and maintenance requirements compared to solar PV. 

There are dozens of Net Zero certification groups nationwide. Each group or program having their own requirements, fees and incentives. We've found most cities & states reference the DOE Zero Energy Ready Home Program (ZERH). Especially, as national rebates and tax incentives for Net Zero construction increase.

For this we designed for the DOE ZERH program.  

As renewable power generation sources are often weather and seasonally dependent, Net Zero is measured by the year.

In the winter for instance: A home's electrical demand is often high, being the increased HVAC demand to heat in the winter and increased lighting loads as it is dark earlier. At the same time, the reduced sunlight hours in winter lead to a reduced production of electricity via solar PV. 

In the summer: A home's electrical demand is reduced and its production is at it's peak. 

By comparing: 

A. The home's electrical use throughout the whole year 

B.  The home's electrical production throughout the whole year 

We find a Net Zero home will have produced more electricity than it used.

We design for average electrical consumption - and then some!

Electrical usage varies greatly based on a home's mechanical equipment needs and occupants habits. For instance, some homes may require a well pump and some families may choose to skip the clothes dryer - and hang dry their clothes. 

It is recommended that you calculate your approximate electrical needs regarding your own habits and preferences. There are a number of online calculators that can assist with this. Once you have determined your approximate electrical usage next determine the Solar Resource Potential of your building area. Determine your solar resource potential factor based on the NREL map at the bottom of this page. 

With your Solar Resource potential in hand - you can determine which of our plans will fit your electrical needs. Within our Plan Book we note the Solar PV Array Production potential for each plan.

On our shop page, you can also sort by array size.

If you find, that you use a lot of electricity: Additional solar PV can often be added as needed on site - Be it an additional ground mount system or a few more modules on East/West facing roof space(s). 

Yes - The DOE Net Zero Energy Ready program, requires a solar PV array design based on a minimum available array area of 300 SF. Our plans often offer much more than 300 SF.

Solar PV array production is based on a number of factors such as geographic location, landscape shading, solar equipment selections etc.  Based on DOE Solar PV design standards we can provide estimates on PV production based on available SF of roof space, roof pitch, azimuth orientation, geographic location and commonly available solar equipment performance factors. Proposed PV array SF does not include roof ridge or edge set-backs which may be required in your building location. Refer to your local building authority.  

It is deceiving but possible to have a Net Zero home that burns fossil fuel. Not our plans. 

Our plans are designed around using electricity, heat pumps and wood pellets - system selections and sizing for all three are provided in each drawing set. 

Simply skip the optional wood pellet stove to build a Carbon Free Net Zero home! 

Side note: There is a growing movement for builders and home owners to track the embodied carbon of building materials as well. There are plenty of resources popping up on this subject. Embodied carbon looks at the carbon emissions throughout a product's life cycle - from production to waste.

We are all about designing for constractor's ease. 

We wanted to provide stock plans that simplify and speed up the Net Zero process. 

In doing so, we were able to provide flexibility. We understand that contractors have their own methods, favorite products and tricks of the trade that work best for them! 

We designed around common insulation materials and 2x6 exterior studs as a basis but we don't require specific building or insulation methods. Always check with your local building authority on their suggested materials & assemblies. However, as long as your assemblies are tight and offer R-32 above grade & below grade basement walls, R-15 continuous under slab, and R-49 roofs - then you're preferred materials/methods are fine by us! 

Our design basis for an R-32 above grade exterior wall is that of:

• Exterior Air Flim (offering approx. R- 0.17)
• Wood/ Vinyl/ Board Siding etc (offering approx. R-0.75)
• 2-1/2" continuous exterior insulation (offering approx. R-12) By use of foam board, insulated zip sheathing or similar insulation materials/methods.
• 2x6 exterior wall filled with 5-1/2" of wool/fiberglass batt or cellulose insulation (offering R-21 to R-23 cavity.)
•  1/2" Interior wall finish ie wood/gyp (offering approx. R-0.45)
• Interior Air Film (offering approx. R-0.68)

Accounting for the reduced assembly R-value at the studs when spaced at 16"oc this assembly offers approx. R-32.06 to R-34.06

We provide sizing & sample selections for various styles of heat pumps at BTF.

All of our stock Net Zero plans come standard with with Air-to-Air mechanical heating/cooling systems ie. Mini-Splits. 

Many of our plans are also available in air-to-water heat pump systems &/or ducted air-to-air heat pump systems. If you are looking for a design that's not our standard mini-split version, simply drop us a quick email if you are interested in a specific heat pump variation for a specific plan!

Air-to-Air: 

Commonly known as mini-split systems. These heat pump systems often have one outdoor unit to one indoor unit. Some manufactures also design for one outdoor unit to serve multiple indoor units. The indoor units may be wall mounted, floor mounted, duct mounted or even ceiling cassettes. 

Air-to-Water:

A common technology in Europe - that has made it's way to the US in the past 5-10 years - There are neat! An Air-to-Water heat pump can provide heating, air-conditioning and domestic heating all with one properly sized system unit. Instead of multiple indoor & outdoor units as you would have with a mini-split system, with Air-to-Water you need only one heat pump for your whole house!  An Air-to-Water system stores the energy gathered within water buffer tanks. These buffer tanks hold hot and cold water, conditioned depending on the operating cycle of the heat pump. Off of these buffer tanks you can heat your home with radiant heat, heat your domestic hot water and even pipe cold water to fan coil units as an AC system in the summer. Operating a single system unit reduces your home's electrical consumption significantly. Especially compared to  operating multiple mini-split systems plus a hot water heater simultaneously. 

For both styles of heat pump, we design around  cold climate heat pumps that operates below zero.

We provided sizing & sample selections for electric wall heaters as a back-up. 

We also provided sizing & sample selections for an optional wood burning pellet stove as another back-up option. Should you like to build a carbon free home - simply skip the optional wood pellet stove!

We  provide a 24/7 energy recovery ventilation design. And if you are interested in one of our homes, but are not ready to go Net Zero - consider our ARCH+ERV variations! This variation will provide you with a plan set that includes the typical industry standard architectural drawings, along with mechanical ventilation drawings. Our mechanical ventilation system drawings provide ductwork sizing  & layouts, unit selections, and air balancing requirements. We also provide sample selections for bathroom exhaust fans and kitchen hoods as required by code.

Cooling loads in tight, Net Zero homes are often quite low due to the reduced thermal transfer inherent of high R-Value insulation. However, should the owner/builder like to add cooling air conditioning (AC), you're provided room by room cooling loads. We recommend mini-split AC systems sized to meet the cooling loads provided in our drawing packages. 

Our Net Zero Plans come with proposed Solar PV array system diagrams, locations and preliminary calculations based on industry standards and solar resource potentials (kW·h/(m2·day)) as found throughout climate zones 5A through 8. For your ease, we provide more data than is required by the U.S. Department of Energy (DOE) Zero Energy Ready National Home Program.  

If you prefer other carbon free HVAC systems, no problem! Our plans provide the details necessary to size them, including 8760 heating & cooling loads on a room by room basis for each climate zone 5A through 8. 

Our plans are designed for cold climates in North America, climate zones 5A through 8. 

Prior to purchase, please check the climate zone of your building site, details below...

Our plans are designed for cold climates. Please check the climate zone of your building site prior to purchase. Our plans provide designs and calculations only for IECC (International Energy Conservation Code) climate zones 5A, 5B, 6A, 6B, 7 & 8.  

Refer to the map below to determine what climate zone your site is located in or refer to the IECC's location list here: https://codes.iccsafe.org/content/IECC2015/chapter-3-ce-general-requirements?site_type=public

None of our plans are designed for construction in the following states:  Alabama, Arkansas, District of Columbia, Delaware, Florida , Georgia, Hawaii, Kentucky, Louisiana, Mississippi, Oklahoma, South Carolina, Tennessee, Texas, Virginia 

Canada: 

The IECC defines each climate zone by common weather patterns and by heating degree days. Canadian Climate Zones are also defined by heating degree days. A technical comparison of the two can be made with the international climate zone table published by the IECC, found at the above link. But we also did the work for you and provide the translation in our plans.

Refer to the link below for a list of heating degree days for locations throughout Canada: https://www.naimacanada.ca/insulation-requirements/?utm_campaign=ecohome&utm_source=ecohome.net&utm_medium=referral&utm_content=/guides/3521/

(We check the functionality of the above links often, however if you find the link no longer works - please let us know!)

 In addition to the calculations, energy analyses and HVAC equipment sizing - All plan sets also come with industry standard  architectural drawings. Including: scaled & dimensioned floor plans, exterior elevations, internal sections & stair sections, roof plans, foundation layout options, door, window & fixture schedules etc. 

Interested in just purchasing the architectural design drawings and would not like any HVAC system info - Feel free to purchase a Basic ARCH plan version. 

 
This is an ideal option for those who love one of our designs but live in a southern climate where our HVAC designs are not applicable.