Indow manufactures advanced secondary glazing systems that improve energy efficiency, indoor comfort, and noise control while preserving existing windows.
Indow
Interior Secondary Glazing
Interior secondary glazing systems that improve window performance without replacing existing windows, reducing drafts, energy loss, and outside noise.
Description
Indow provides advanced interior secondary glazing systems that improve the energy efficiency, comfort, and acoustic performance of existing windows without requiring full window replacement.
IndowPRO is a modular secondary glazing system designed for commercial applications. It accommodates out-of-square window frames, delivers an ultra-low air leakage rate of 0.01 CFM, and, when paired with Vacuum Insulated Glass (VIG), achieves up to R-13 thermal performance when installed over aluminum single-pane windows.
IndowONE window inserts are designed to reduce drafts and stabilize indoor temperatures in existing buildings. They help address common window performance issues while providing up to 20% energy savings and reducing outside noise.
Key Differentiators
Custom manufactured - Each insert is built to the exact dimensions of the existing window, accommodating irregular frames for a precise fit.
High-performance air sealing - Compression tubing creates a near-airtight seal that minimizes drafts and air leakage.
Simple installation - No tools or modifications to the existing window frame are required, allowing for quick installation with minimal occupant disruption.
Lower-cost retrofit - Provides an alternative to full window replacement while improving energy efficiency, comfort, and noise control.
Use Cases
Seal/upgrade your windows
Cost Savings
IndowPRO with Vacuum Insulated Glass can reduce energy loss through windows by more than 95%, lowering heating and cooling loads while reducing HVAC operating and maintenance costs.
About
Decarbonization Impacts
Operational Emissions
Interior secondary glazing systems reduce heating and cooling energy demand by minimizing energy loss through existing windows, lowering operational emissions.
Embodied Carbon
By retaining existing windows rather than replacing them, secondary glazing reduces material waste and the embodied carbon associated with window replacement.
Project + Building Compatibility
Project Type
Existing building retrofit
Essential Building Characteristics
Window frames must have 1 1/2" of flat space on inside of frames or at least 1" of flat space on face of frames, with no obstructions such as shutters, shades, handles, cranks, or locks.
Ideal Building Characteristics
Existing windows with a compatible interior window frames with at least 1.37" of flat mounting space. A 3 to 6" gap between the primary window and the insert provides optimal acoustic performance.
Minimum Project Size
1 window
Ideal Project Size
10 to 10,000 windows
Additional Considerations
Window dimensions are collected using either a laser measurement kit or standard tape measure before manufacturing.
NY Contractor Availability
Installation contractors are available throughout New York.
Other Screening Criteria
IndowPRO is for inoperable windows / non-egress windows. IndowONE inserts are removable and can be installed on operable windows.
Example Installations
Installed By
U.S. Department of Energy; Pacific Northwest National Laboratory; Bowdoin College; This Old House
Case Studies
Resident Experience
During Installation
Installation typically takes approximately 15 minutes per window with no modifications to the existing window frame, minimizing disruption to occupants.
Post Installation
Building occupants experience reduced drafts, quieter indoor spaces, more stable indoor temperatures, reduced outdoor pollutants and pollen infiltration, and less window condensation.
Financing
NY Incentives/Financing Resources
Con Edison offers incentives for secondary glazing projects through its energy efficiency programs:
$0.45 per annual kWh saved, or
$15 per annual therm saved, depending on the type of energy savings achieved.
Payback Period
5 to 12 years.
Upfront Costs
IndowPRO systems with Vacuum Insulated Glass typically cost approximately $40 per square foot, plus installation labor.
Ongoing Costs
There are no ongoing costs associated with IndowPRO or IndowONE.
Operations, Management, and Maintenance
Operations and Maintenance Requirements
IndowPRO with Vacuum Insulated Glass can be cleaned with typical window cleaners. IndowONE should be cleaned with diluted dish soap and a microfiber cloth.
Ease of Operations
Indow provides ~30 minute training for user training following installation.
Service Support
IndowPRO and IndowONE systems require minimal maintenance and generally do not require specialized service contractors. Routine maintenance can typically be performed by in-house building maintenance staff.
Moisture Management
The interior inserts help reduce condensation by limiting interior moisture from reaching the existing window glazing.
Future Proofing
IndowPRO is backed by a 20-year commercial warranty. IndowONE inserts include a lifetime residential warranty.
Specifications
IndowPRO has completed AERC air infiltration testing and ASTM E90-23 acoustic testing. IndowONE are AERC tested and certified.