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The Treetop ADU demonstrates how a compact high-performance ADU can achieve exceptional energy efficiency without sacrificing comfort or design. This 738 sq ft studio delivers a HERS score of 30 (excluding solar) and an ultra-tight envelope at 1.1 ACH50 – placing it among the most airtight residential buildings in the Twin Cities metro area, and in the U.S. For homeowners seeking a Net Zero ready ADU, the Treetop ADU project proves that advanced building science and all-electric systems create healthy, durable, and low-cost living spaces.
Results and StatsBeds: 1
Baths: 1
Square Feet: 738
Air Leakage: 1.1 ACH50
HERS Score (without solar): 30
ENERGY SYSTEM: All-electric, heat pump + ERV, Net Zero ready
CERTIFICATIONS: DOE Zero Energy Ready, ENERGY STAR, EPA Indoor airPlus, MN GreenPath Master Level
Paltrin designed the Treetop ADU to provide flexible, independent living space while targeting near-Net Zero energy performance through a superior building envelope and high-efficiency mechanical systems. Our goals were to maximize comfort and indoor air quality within a compact studio footprint, reduce long-term operating costs to near zero, and eliminate on-site fossil fuels entirely. We achieved every performance target by integrating continuous insulation, meticulous air sealing (verified by 1.1 ACH50), triple-pane windows, and all-electric heat pump technology with an energy recovery ventilator (ERV). The result is a healthy, durable, and ultra-efficient ADU that sets a new benchmark for sustainable accessory dwelling units in Minnesota. The home’s DOE Zero Energy Ready, ENERGY STAR, EPA Indoor AirPlus, and MN GreenPath Master Level certifications validate that we met the highest standards for energy efficiency, durability, indoor air quality, and overall green building performance.
The Treetop ADU’s 1.1 ACH50 air leakage result is among a high-performance crop of residential buildings. We achieved this through meticulous air sealing at every penetration, joint, and transition, combined with a continuous insulation strategy that eliminates thermal bridging. High-performance triple-pane windows and superior wall and roof insulation create an envelope that maintains stable indoor temperatures with minimal mechanical system runtime. This ultra-tight envelope is the primary reason for the home’s HERS 30 rating and ensures consistent comfort regardless of outdoor conditions.
To achieve near-Net Zero performance, the Treetop ADU features a fully electric mechanical system designed for maximum efficiency and low environmental impact. A high-efficiency ductless heat pump handles all heating and cooling needs, while an energy recovery ventilator (ERV) delivers continuous fresh, filtered air without losing conditioned energy. This all-electric approach eliminates on-site fossil fuel combustion, improves indoor air quality, and positions the ADU for true Net Zero once paired with solar photovoltaic generation. For Twin Cities homeowners, this translates to energy bills that are near zero year-round.
Despite its efficient 738 sq ft footprint, the Treetop ADU feels spacious and welcoming through strategic studio planning and abundant natural daylighting. Carefully positioned windows optimize passive solar heat gain in winter and provide natural cross-ventilation in summer, actively reducing mechanical cooling needs. The flexible studio layout adapts easily to long-term residence, guest quarters, or rental income in the Minneapolis-St. Paul market, while the thoughtfully designed bathroom maximizes accessibility and comfort. This project proves that a small ADU can be both highly functional and deeply connected to the outdoors.
Whether you’re exploring an ADU for rental income, multigenerational living, or increasing your Minnesota property value, Paltrin brings proven expertise in achieving the highest certifications and performance levels. Contact us to discuss your project.
The Treetop ADU expands the functionality and value of the property by adding a flexible, independent living space that can adapt to guests, family, rental income, or long-term living needs. Built to exceptionally high performance standards, the ADU delivers near-Net Zero energy efficiency through an ultra-tight building envelope and all-electric systems that dramatically reduce energy use and operating costs. The result is a comfortable, healthy, and future-ready space that enhances both the homeowner’s lifestyle and the long-term value of their home.