The Energy Efficiency Trade-Off
New construction and renovated energy-efficient homes are more comfortable, less expensive to operate, and better for the environment than older, leaky construction. They're also different in ways that matter for emergency preparedness.
The same insulation and air sealing that keeps your heating bills low also means combustion products build up faster. The heat pump that efficiently heats your home at 250% electrical efficiency provides zero heat when the grid fails. The all-electric kitchen that eliminates gas combustion risk leaves you with no cooking capability in a power outage.
None of these are arguments against energy efficiency. They're arguments for understanding your specific home's failure modes and planning accordingly.
The Tight Building and CO Risk
Modern homes built to IECC 2012 or newer codes have air infiltration rates around 3-5 ACH50 (air changes per hour at 50 pascals — the standard measurement). Older homes built before energy codes were common might be 15-30 ACH50 or higher.
What this means practically: a combustion heat source in a tight modern home depletes oxygen and builds up CO much faster than the same source in an older home.
The CO detector is not optional in a tight home. If you use any combustion source — propane heater, camp stove, generator near an open window — have a CO detector in the space. CO is colorless and odorless. Symptoms (headache, nausea, confusion) are easy to attribute to other causes. CO poisoning kills people who think they're just feeling unwell.
The ventilation requirement:
- Portable propane heaters (Mr. Heater and similar): rated for indoor use, but "indoor use" assumes a more air-porous structure than a tight modern home. If you use these in a modern home: window open 2-3 inches minimum, CO detector active.
- Camp stoves: not rated for indoor use. Never use inside without significant ventilation.
- Generator: never inside. CO from generators has killed people in attached garages with the door open. The engine exhaust must be entirely outside and downwind from any opening.
The mechanical ventilation dependency: Many tight modern homes rely on mechanical ventilation (HRV or ERV — heat recovery ventilator or energy recovery ventilator) for fresh air exchange. During a power outage, this system stops. The home has lower air exchange than it was designed for. This is another reason to open a window during extended outages, both for fresh air and to provide safe CO dilution if any combustion is occurring.
All-Electric Home Power Planning
The trend toward all-electric homes (heat pump for heating and cooling, electric range, electric water heater) eliminates natural gas dependency but creates complete electricity dependency.
The backup power challenge for all-electric homes:
Natural gas furnace: typically runs on a modest amount of electricity (circulator, controls, blower) — 400-800 watts. Runs on a mid-size generator.
Air source heat pump: runs on 2,000-5,000 watts in heating mode. Requires a large generator to run during a power outage.
Electric resistance heat (baseboard, strip): 1,000-2,000 watts per zone. High consumption, but individual zones can be managed.
The practical solution for all-electric homes:
Option 1: Whole-home standby generator (10-22 kW) with automatic transfer switch. This handles a heat pump and all other loads seamlessly during an outage. Appropriate for regions with frequent outages or all-electric homes with no combustion backup.
Option 2: Battery backup system (2-3 Tesla Powerwall or equivalent) plus solar. This handles most loads including modest heat pump use during sunny periods; may struggle with heat pump in extended cold, cloudy weather.
Option 3: Supplemental combustion backup. In new all-electric homes, a propane or natural gas backup heating source — even a single wall-mounted vent heater in the most-used room — provides heating capability independent of electricity. This requires a combustion appliance in an otherwise electric home, but provides genuine resilience.
Option 4: Electric panel heater and good insulation as a fallback. A modern well-insulated home loses temperature slowly enough that a 1,000W portable electric heater run from a battery station can maintain survivable temperatures in one room for extended periods.
Temperature Retention in Modern Homes
The high insulation values of modern homes are a genuine emergency advantage. A well-insulated home is much slower to drop to dangerous temperatures than older construction.
Approximate heat retention by insulation level:
A typical older home (R-11 walls, minimal ceiling insulation) at 70°F interior with 20°F outside temperature loses approximately 2-4°F per hour with no heat source.
A modern energy-efficient home (R-21 walls, R-49 ceiling, good windows) at the same conditions loses approximately 0.5-1°F per hour.
This difference is significant: the older home reaches 40°F (pipe freezing risk) in roughly 8-15 hours. The modern home might maintain safe temperatures for 24-48 hours. That's the difference between "manage it tonight and get help tomorrow" and "you have time to develop a plan."
The one-room strategy in a modern home:
If backup heating is limited, consolidate in the best-insulated interior room. Close off unused spaces. The smaller the space you're maintaining, the more effective limited heat sources are. A 200-square-foot bedroom with good insulation and a small 1,500W electric heater drawing from a battery station holds temperature far better than trying to heat the whole house.
Cooking in All-Electric Homes
An all-electric kitchen provides no cooking capability during a power outage. This is a genuine planning gap that many all-electric homeowners haven't thought through.
Backup cooking options (by practicality):
Butane camp stove: small, portable, requires no installation, runs on standard butane canisters. One to two burners; adequate for most emergency cooking. Keep one and a 12-pack of canisters in your emergency supplies.
Propane camp stove (Coleman-style or similar): more powerful than butane, uses widely available propane canisters or 20-lb tanks. More setup required. Good outdoor cooking capability.
Outdoor gas grill (propane or natural gas): most homes with grills have one; propane grills work when natural gas service is interrupted. Never cook on a propane or charcoal grill indoors.
Wood-burning fireplace: if your home has a functional wood-burning fireplace, you can cook in it. Requires practice — cooking in a fireplace with cast iron is a skill, but it works.
The no-cook alternative: Stock enough food that doesn't require cooking to handle 72-hour outages without any cooking capability. Protein bars, peanut butter, crackers, canned food you can eat cold, nuts, dried fruit. This is the simplest approach for short outages.
Water Heater and Hot Water During Outages
Traditional tank water heaters (gas or electric) maintain a reservoir of hot water. After the power goes out, your electric water heater stops heating but the insulated tank keeps the existing water hot for 2-6 hours.
Heat pump water heaters — increasingly common in new construction for efficiency reasons — are electric and fail during power outages. There's no tank of stored hot water unless the tank itself was hot when the power failed.
On-demand (tankless) water heaters: Gas-fired tankless heaters require electricity for ignition and controls; they will not function during a power outage even with gas supply maintained. This is a surprise to many homeowners.
For preparedness purposes, an extended power outage means no hot water from any electric or electronically-controlled water heater. Cold showers are an inconvenience; plan for them. For health and hygiene purposes, water heated on a camp stove provides enough for critical needs.
Sources
Frequently Asked Questions
Why can't I use a propane or kerosene heater in a tightly sealed modern home?
Modern homes built to current energy codes are intentionally air-sealed — infiltration rates are very low compared to older construction. When you burn a combustion heat source indoors (propane heater, kerosene heater, gas stove for heat), it produces carbon monoxide, CO2, and depletes oxygen. In a drafty older home, sufficient air infiltration dilutes these byproducts. In a tight modern home, CO can reach dangerous concentrations much faster. If you use any combustion heat source in a tight home, you MUST open a window at least a crack (1-2 inches), and you MUST have a functioning CO detector.
What happens to a heat pump during a power outage?
Nothing good — heat pumps require electricity to run and provide no heat or cooling during a power outage. Unlike natural gas furnaces (which can sometimes run on a generator with modest power consumption), heat pumps are large electrical loads (2,000-5,000 watts running). Running a heat pump on a portable generator is possible but requires a large, appropriately-sized generator. The transition to all-electric homes eliminates the natural gas furnace as a moderate-load backup, making generator sizing for heat a more significant planning challenge.
Are new, energy-efficient homes more resilient in power outages, or less?
More resilient in terms of temperature retention — a well-insulated modern home loses heat or gains heat much more slowly than older construction, giving you more time before the interior temperature becomes dangerous. Less resilient in terms of flexibility — when your only heat source is electric (heat pump, electric resistance), a grid-down event takes all heating capability simultaneously, with no combustion backup option built in.