Why All-Electric Forced Induction Ranges Into All 213 Units

If you are pricing an all-electric multifamily project under the Massachusetts Stretch Code, the appliance package is probably still sitting in the interior design column of the budget. On a recent 213-unit project, that assumption broke. We modeled the all-electric and mixed-fuel scenarios side by side, and the all-electric version would not pass HERS until every kitchen moved to induction and every laundry moved to a heat pump dryer. Not because anyone wanted those appliances. Because the electric water heater opened a HERS deficit large enough that we had to harvest every point in the building to close it.

The Real Project Numbers

The project was a 213-unit multifamily building under the Massachusetts Stretch Code. The developer asked the standard question at the front of design. Gas or all-electric. We modeled both fuel scenarios against the same envelope and the same HERS target so the only variable that moved was the fuel path.

The mixed-fuel version passed easily. Standard electric ranges. Vented electric dryers. The gas water heater carried enough efficiency cushion in the model that the appliance package never came under pressure. The team could spec whatever cooktop and laundry equipment fit the unit finish budget.

The all-electric version failed at first pass. The same envelope, the same HVAC, the same window spec. The single change that flipped the result was the water heater. Once the gas water heater came out and an electric water heater went in, the model lost enough ground that the building no longer cleared its HERS target.

To recover, we had to upgrade every kitchen in all 213 units to induction and every laundry to a heat pump dryer. Those two moves pulled back the points the water heater gave up. That is not a finish decision. That is an energy code decision worth hundreds of thousands of dollars once it multiplies across the unit count.

The HERS Deficit Behind the Spec

Domestic hot water is one of the largest end-use loads the HERS model tracks in a dwelling unit. When the water heater is gas, the model counts the site energy at the efficiency of the gas appliance and the rating reflects that. When the water heater is electric, the load runs through the source energy penalty that electricity carries in the rating, and the unit gives up ground.

That lost ground has to be recovered somewhere. The HERS Index is a whole-building number. Every end use that the model can credit becomes a candidate to close the gap. Cooking and laundry are two of the few end uses left after the envelope, the HVAC, and the ventilation are already specified.

Induction cooktops draw less energy than standard electric resistance ranges for the same cooking output, and the model credits the difference. A heat pump dryer uses a fraction of the energy of a vented electric dryer, and the model credits that too. Stacked across 213 units, those two appliance upgrades move the rating enough to put the all-electric building back over the line.

The mixed-fuel building never needed any of that. The gas water heater kept the deficit from opening in the first place, so the appliance package stayed a free choice. Same building, same units, two completely different appliance budgets driven entirely by one piece of mechanical equipment.

When Appliances Stay a Free Choice

The appliance package is not always an energy code decision. There are project configurations where it stays in the finish column.

Mixed-fuel buildings with a gas water heater. When the water heater is gas, the HERS deficit does not open and the model has no reason to pull points out of the kitchen and laundry. The developer specs appliances on finish budget alone.

All-electric buildings with envelope headroom to spare. If the envelope and HVAC are already well above the HERS target, the building can absorb the electric water heater penalty without touching the appliances. The headroom does the work the induction range would have done.

Projects where the appliance upgrade was already in the spec. Some developers spec induction and heat pump dryers as a marketing or durability decision before the energy model runs. On those projects the model simply credits a choice that was already made.

Buildings targeting a less strict code path. A project under base code rather than the Stretch Code has a different target, and the appliance package may never come under pressure regardless of the fuel choice.

The Decision Framework

If you are pricing an all-electric multifamily building under the Stretch Code, run the HERS model before you finalize the appliance spec. The water heater choice is quietly writing your kitchen and laundry budget, and the number it writes can run into the hundreds of thousands once it multiplies across the units.

The mistake is treating the appliance package as a finish decision that lives downstream of the energy model. On an all-electric building it lives upstream. The fuel path for the water heater sets the size of the HERS deficit, and the deficit decides whether your cooktops and dryers are a design choice or a compliance requirement.

No two buildings land in the same place on that curve. A project with a generous envelope might carry the electric water heater with no appliance upgrade at all. Another might need every point that induction and a heat pump dryer can give. The way to know which one you are holding is to model your building before the spec is locked, which is the entire reason we run the fuel scenarios side by side at the front of design.