Industry
How to read an all-electric home case study properly
How to judge a published all-electric conversion story, what a credible case study must disclose, and how to build a documented record of your own house.
What to take away
- A credible case study discloses seven itemsclimate, house vintage, baseline fuel use, boundary, conversion basis, costs and measurement period.
- Three gaps or more and it is one household's story, not evidence you can spend.
- Savings figures do not move between houses. The sequence of decisions does.
- Your own log, kept as you go, is the only case study that fits your house.
- Utility programs and state energy offices publish documented projects. Score them with the checklist below.
The seven disclosures a credible case study makes
A saving figure without context is decoration. Run any published conversion story past this list before you accept its numbers.
Seven disclosures
- Climatea design temperature or hardiness zone, so a coastal result is not read as a cold-climate one.
- House vintage and envelopeyear built, insulation levels, window type.
- Baseline fuel usea full year of therms, gallons or kWh before the work started.
- Boundarywhich loads sit inside the comparison and which were left out.
- Conversion basisthe tariff, the emissions factor and the year both come from.
- Costsequipment, labor, permits and panel work, listed apart from any rebate.
- Measurement periodthe dates of the before and after windows.
Three gaps or more and the study cannot carry a general conclusion. It can still be interesting reading about one house.
Case study disclosure checklist
- Climatelocation, design temperature
- Housevintage, floor area, envelope
- Baseline12 months usage by fuel
- Scopereplaced, added, left alone
- Weather normalizationdegree days adjusted
- Ratestariff before and after
- Fundingwho paid for write-up
Why savings figures do not transfer between houses
Outcomes shift with climate, envelope, the outgoing fuel, local tariffs and installation quality. Change one and the result moves.
A conversion that halved a bill in a cold, leaky, oil-heated house says little about a mild-climate house on cheap gas with good insulation. Same equipment, different arithmetic.
Read the decision structure. How the work was sequenced, what surprised the owner, where the money went. Those travel between houses. The dollar figure does not.
Equipment choice drives most of the variance, and our comparison of heat pump types on value, upkeep and fit sets out which shape suits which house and fuel situation.
Example: scoring a published study against the checklist
This composite is built from the disclosure list rather than from a named house. The reasoning is what carries over.
A program page reports a four-figure annual saving after an oil-to-heat-pump switch. Score the seven items.
Scoring a published study
- Climatenamed as a region, no design temperature. Weak.
- Vintage1960s build, stated with insulation level. Strong.
- Baselineone winter of oil bills, not a full year. Weak.
- Boundarywater heating replaced but excluded from the comparison. Weak.
- Conversion basistariff year unstated. Weak.
- Costsrebate netted into the total. Weak.
- Measurement periodtwelve months after commissioning. Strong.
Two strong items and five weak ones. The saving is real for that house. It is not a benchmark for yours.
A single gap is normal in a short write-up. Five gaps mean the headline number was never built to travel.
If the measurement period is the shaky item, what a home energy monitor can actually tell you explains why a monitoring claim can be softer than it sounds.
Building your own record, stage by stage
The only case study that applies to your house is your house. Start before the first quote arrives.
Building your own record
| Stage | What to capture |
|---|---|
| Before any quote | Twelve months of fuel bills in therms, gallons or kWh, plus any blower door result |
| Scope and bids | What each bid includes and excludes, and the load calculation behind the panel decision |
| Permits and inspection | Permit number, inspector notes, final sign-off |
| Commissioning | Model numbers, settings, flow rates or refrigerant charge, and the start date |
| First year | Monthly consumption beside degree days, so weather cannot hide inside the total |
| Two-year review | The comparison you wanted, now covering two heating and two cooling seasons |
Build your own case study
- Before12 months usage, equipment ages
- Designload calculation and assumptions
- Quotesscope, exclusions, bid changes
- Installcommissioning, permits, inspections
- Afterusage per degree day, two years
- Reflectionwhat to sequence differently
Reasonable record-keeping beats a perfect spreadsheet. Monthly readings and a folder of documents will do. The lessons on installing residential energy monitors cover the practical side of capturing a baseline without guessing.
Where to find credible published case studies
Program administrators publish the projects they funded. A state energy office such as the Massachusetts Department of Energy Resources funds work through programme administrators and points to their published material.
Federal work sits with the DOE's Analysis and Strategy Office, which turns program data into evidence about what interventions do at scale.
For the national frame your house sits inside, the EIA's U.S. energy facts covers consumption and production by sector.
If you are still choosing equipment rather than judging someone else's project, the home electrification starting guide runs through the order of work.
