Straw-Wrapped Home

Straw-bale home construction has been around for some time, but this project, done by Keith Warren, owner/operator of Straw Wrapped Homes, is a made-in-Alberta approach to using straw bales for a deep energy retrofit. In 2017, Keith used his technique on a 1963 Bungalow, and has lived in the home since 2020.

Building Type	Single-Family Bungalow	Location	Drayton Valley, AB
Year Built	1963	Foundation Type	Concrete (Full Basement)
Structure Type	Wood-Framed	Climate Zone	7a
Heating Degree Days	5120	Retrofit Status	Complete
Year Completed	2017	Retrofit Phasing	No

Project Team

Straw Wrapped Homes

Project Priorities

Reduce Energy Consumption
Achieve Net Zero or Net Zero Ready
Increase Thermal Comfort
Reduce GHG Emissions

Upgrades

R40 Strawbale exterior wall Insulation
New exterior, including stucco and metal roof
R60 fibreglass insulation/6 mil vapour barrier
High performance windows and doors
R20 interior insulation added to basement
HRV, electric heating, electric hot water tank
8.5 kW of Solar
200 Amp Electrical Service

Project Description

Keith Warren developed this process himself (he owns the patents) for attaching straw bales to the exterior of a home in a way that allows the air to flow through the straw. This prevents condensation and protects the straw bales from the elements. What’s more, straw is a locally available by-product of agriculture, and sequesters more greenhouse gasses than is required to plant, harvest and store. Warren’s system adds an R value of 40 to the building in addition to what it already has. Since 2020, the home’s 8.5 kWh solar has provided all the energy requirements of the building, which is completely electrical. The home is tied to the grid, but generates more power than what is purchased during overcast days and extreme temperatures in the summer and winter.

Before & After

General
	Before	After
Building Condition	Before Minimally improved from it’s original 1960’s condition. Frequent temperature swings	After Full refinish on the interior in addition to the exterior and envelope improvements
Comfort	Before Typical drafty 60’s construction. Frequent temperature swings	After Limited temperature swing in both heating and cooling seasons, significant reduction of exterior sounds

Envelope
	Before	After
Ceiling/Attic Insulation	Before R15 (estimate), wood shavings	After R60 fiberglass extends across the top of the straw bale insulation column, 6 mil vapour barrier.
Foundation Insulation	Before 2×4 framing with 1/4″ paneling	After R40 straw wrap/ 8″ above grade, R20 fiberglass interior walls to footings/floor joists R40 fiberglass/ 6 mil vapour barrier to footings
Wall Insulation	Before R8 fiberglass, no vapour barrier. Twenty-minute fire burn rating.	After R12 fiberglass, 6 mil vapour barrier, R40 exterior straw wrap, building paper and new stucco. 2-hour fire burn rating.
Windows and Doors	Before Aluminum sliders	After Triple glazed, triple low E coating, double Argon gas fill between panes, PVC frames. All windows are recessed on the exterior to reduce wind effect on the surface

Mechanical & Electrical
	Before	After
Heating	Before 1980 gas furnace	After Individual room thermostatic controlled- electric base board heaters, sized for individual room heat loss.
Cooling	Before None	After No mechanical cooling system required because of the superior insulation envelope.
Hot Water	Before 1980 pilot lit gas fired hot water tank	After Standard 40-gallon electric hot water tank which utilizes room air temperature to raise the incoming water temperature from +3C to +15C. All sinks in home have ‘on demand’ electric heaters for source point hot water.
Ventilation	Before None	After Broan 7.1 HEPA (Heat recovery ventilation system) With 70’ of 4” plastic pipe below grade in the crawl space to pre-heat incoming fresh air (air intake -30C temperature is +7 C at the HRV intake/Summer temperature +25C is reduced to +15C at HRV intake supporting air cooling.
Renewables	Before None	After 8.5 KWH solar panels on roof, metal raised rib roof allows solar panels to be attached without roof penetration. EV Charging station in new double garage.
Electrical Service	Before 100 Amps	After 200 Amps

Straw-Wrapped Home

Project Team

Project Priorities

Upgrades

Project Description

Before & After

General

Building Condition

Before

After

Comfort

Before

After

Envelope

Ceiling/Attic Insulation

Before

After

Foundation Insulation

Before

After

Wall Insulation

Before

After

Windows and Doors

Before

After

Mechanical & Electrical

Heating

Before

After

Cooling

Before

After

Hot Water

Before

After

Ventilation

Before

After

Renewables

Before

After

Electrical Service

Before

After

Photos