Indiana’s energy conservation code requirements apply to Class 1 structures and are set by ASHRAE Standard 90.1-2007 with Indiana-specific amendments, adopted by the Fire Prevention and Building Safety Commission and effective May 5, 2010.1U.S. Department of Energy. Indiana – Building Energy Codes Program If you are designing, permitting, or building a commercial, industrial, or large multifamily project in Indiana, this is the standard your envelope, HVAC, and lighting must meet.
Which Buildings the Code Covers
The code applies only to Class 1 structures. Under Indiana law, a Class 1 structure is any building or portion of a building occupied or used by the public, by three or more tenants, or by one or more employees of another person.2Indiana Department of Homeland Security. IC 22-12-1-4 Class 1 Structure That pulls in office buildings, hospitals, hotels, retail stores, warehouses, factories, and apartment buildings with three or more units. A single area open to the public or staffed by an employee can move an entire building into Class 1.
One- and two-family homes and townhouses fall under a separate classification and follow the Indiana Residential Code instead.3Indiana General Assembly. Indiana Code 22-12-1-5 Class 2 Structure Getting this call wrong at the start of design causes permitting delays and, sometimes, expensive rework. A building that looks residential but contains three or more separate tenant units is Class 1 and answers to the energy code discussed here.
Three Compliance Paths
ASHRAE 90.1-2007 gives you a choice of three ways to show compliance, and Indiana accepts all three.
The prescriptive path is the most direct. Every insulation R-value, fenestration U-factor, lighting power density, and HVAC efficiency rating must meet its number in the code’s tables. No modeling, no tradeoffs.
The simplified approach is available for smaller buildings with straightforward, typically single-zone HVAC. It uses fewer forms and calculations but still enforces the mandatory minimums for the envelope, lighting, and mechanical systems.
The energy cost budget method is performance-based. Using energy simulation software, you show that the projected annual energy cost of your design does not exceed the cost of a code-compliant baseline building. This route allows tradeoffs: a weaker envelope in one place can be offset by a more efficient mechanical system elsewhere, so long as the total energy budget holds.
Certain provisions are mandatory on every project regardless of path. Air leakage limits, duct sealing, and minimum equipment efficiencies cannot be traded away, even under the energy cost budget method.
Building Envelope Minimums
Indiana straddles two climate zones: Zone 4 in the south and Zone 5 through the north and center. Envelope requirements tighten as you move north.4Indiana Department of Homeland Security. ASHRAE 90.1-2019 Comparison and Supplement The prescriptive tables set maximum U-factors and minimum R-values for every envelope component: roofs, above-grade walls, below-grade walls, floors, slab edges, and opaque doors.
Commercial roof assemblies with insulation entirely above the deck require a minimum of R-20 continuous insulation. Attic assemblies need R-38. Steel-framed above-grade walls in Zone 5 require R-13 cavity insulation plus R-7.5 continuous insulation, with somewhat lower wall requirements in Zone 4. These are baselines; many designers exceed them to lower long-term operating costs.
Windows, Skylights, and Glazed Doors
Fenestration is regulated through two numbers: U-factor, which measures heat transfer through the assembly, and Solar Heat Gain Coefficient, which measures how much solar radiation gets through. Lower is better for both. Limits shift depending on the percentage of wall area covered by glazing and whether the framing is metal or nonmetal. Buildings with more than 40 percent glazed wall area face stricter per-window performance requirements.
Air Sealing and Moisture Control
Every joint, penetration, and transition in the envelope must be sealed, caulked, gasketed, or weatherstripped. The code specifically calls out joints around window and door frames, wall-to-foundation connections, building corners, utility penetrations through roofs and walls, and any assembly used as a duct or plenum. Fenestration products must be tested and labeled for air leakage: glazed swinging entrance doors cannot exceed 1.0 cubic feet per minute per square foot, and all other products are limited to 0.4 cfm per square foot. Vapor retarders are required to control condensation inside wall and roof assemblies.
HVAC Requirements
The mechanical section sets minimum efficiency ratings for every category of heating, cooling, and heat pump equipment. The metric depends on the equipment: EER for rooftop units, SEER for split systems, and COP in heating mode for heat pumps. These minimums apply regardless of compliance path.
System-level rules also apply. Buildings with cooling capacity above 54,000 BTU per hour must include an air or water economizer that uses outside air for free cooling when conditions allow.4Indiana Department of Homeland Security. ASHRAE 90.1-2019 Comparison and Supplement All ductwork must be sealed and insulated so conditioned air does not leak into ceiling plenums, mechanical chases, or other unconditioned spaces. Complex systems (variable-air-volume setups with multiple zones, chillers, and cooling towers) trigger additional controls requirements, including demand-controlled ventilation and optimized equipment staging, that do not apply to a simple single-zone rooftop unit.
Fan systems with a total motor nameplate horsepower above 5 hp must stay within allowable fan power limits calculated from design airflow. That keeps designers from oversizing fans, which wastes energy at the partial-load conditions that dominate most of the year.
Lighting Power and Controls
Lighting is often the largest energy end use in a commercial building, and the code caps it through power density limits in watts per square foot. You may use either the building area method, which applies one allowance to the whole building based on primary use, or the space-by-space method, which assigns limits room by room based on function.
Typical building-area allowances include 1.0 W/ft² for offices, 1.5 W/ft² for retail, 1.2 W/ft² for hospitals and schools, 0.7 W/ft² for multifamily common areas, and 0.3 W/ft² for parking garages. Space-by-space usually yields slightly more total wattage because it accounts for high-need areas like lobbies and conference rooms individually, but the documentation burden is heavier.
Automatic shutoff is not optional. Every space must have an occupancy sensor, a time clock, or a scheduling system that turns lights off when the space is unoccupied. Exterior lighting has its own power limits. These rules apply to new construction and to substantial lighting renovations in existing Class 1 buildings.1U.S. Department of Energy. Indiana – Building Energy Codes Program
Exemptions
Not every Class 1 building is bound by every provision. Historic buildings can qualify for exemptions if they meet one of the following: listing on the State or National Register of Historic Places, designation as historic under a local or state law, certification as a contributing resource within a listed historic district, or a State Historic Preservation Officer opinion that the building is eligible for listing.5U.S. Department of Energy. What Is Required for Historic Buildings Age alone does not qualify a building. Registration or documented eligibility does.
Very low energy use buildings, such as unheated storage or certain agricultural structures, may also fall outside the code’s scope. Any addition to an exempt Class 1 building, however, must comply on its own. Confirm any exemption with the local jurisdiction before designing to it.
Documentation and Plan Review
Compliance begins on paper. Most Indiana projects use COMcheck, a free U.S. Department of Energy tool that accepts Indiana’s code as a jurisdiction and generates compliance reports for envelope, lighting, and mechanical systems.6U.S. Department of Energy. COMcheck Projects using the energy cost budget method typically need full energy modeling software instead.
The compliance reports and signed statements go directly into the construction documents, usually on the cover sheet or in dedicated schedules within the drawing set. They must identify R-values for each insulation assembly, U-factors and SHGC for fenestration, the lighting power density calculation, and HVAC equipment efficiency ratings. Plan reviewers at the Indiana Department of Homeland Security, or a local building department with its own review authority, compare these specifications against code requirements before issuing a design release.7Indiana Department of Homeland Security. Building Plan Review Construction cannot start until the design release is in hand. Building this documentation into the design phase is far cheaper than discovering gaps after construction drawings are finished.
Field Inspections
Once construction is under way, inspectors verify that what is being built matches what was approved. The most critical energy inspection happens at rough-in, before walls and ceilings close up. Inspectors check insulation placement, vapor retarder installation, duct sealing, and air barrier continuity while everything is still visible. Once drywall goes up, verifying these items becomes destructive and expensive. A final inspection confirms lighting controls function, mechanical equipment matches specified efficiencies, and the building is ready to occupy. Passing leads to a Certificate of Occupancy, without which the building cannot legally be used.
Where This Code Sits Compared to Newer Editions
ASHRAE 90.1 is on a three-year update cycle, and Indiana’s 2010 code is now several editions behind. Under newer versions of the standard, roof insulation for climate zones like Indiana’s rises from R-20 to R-30 for above-deck assemblies, and attic insulation from R-38 to R-49.4Indiana Department of Homeland Security. ASHRAE 90.1-2019 Comparison and Supplement Wall and slab requirements have tightened, and later editions introduce items that did not exist in the 2007 version, including on-site renewable energy, thermal bridging calculations, tighter damper leakage limits, and updated efficiency metrics like SEER2 and HSPF2.8ASHRAE. Standard 90.1 – Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings
Indiana’s Building Code Update Committee has been reviewing newer model codes, but until a formal adoption occurs, ASHRAE 90.1-2007 with Indiana amendments remains the enforceable statewide standard. On a building that will operate for decades, the cost difference between code minimum and a higher-performance envelope or HVAC package is usually small compared with lifetime energy costs, which is why many designers voluntarily build above the current minimums.