Projects / Multifamily      Portland, Maine

Cumberland Triplex


Portland’s popular Munjoy Hill neighborhood is the perfect spot for multi-unit housing. This previously undeveloped lot on Portland’s East End is within walking distance to restaurants and shops, with easy access to public transportation. It was bound to be a great spot for renters looking for the best of city life and close to amenities like the Eastern Promenade and views of Casco Bay’s islands and sailboats.

With increasing fuel prices and intensely cold Maine winters, the client wanted an ultra-efficient building that would keep heating costs low without sacrificing comfort, especially considering that our client was planning to live onsite.


The building has an owner’s apartment on the top two levels and two apartments for tenants. The four-story apartment project is one of the most technically sophisticated buildings in Maine. Its construction costs were similar to any traditionally built building, but the monthly utility bills are negligible. The building generates enough energy over the course of the year to be more than net-zero energy efficient.

The building features super-tight construction, highly efficient insulation, air-source heat pumps, and a heat recovery ventilation system. Ninety solar hot water tubes heat three hot water tanks for all the units.


  • Year Completed

  • Cost

  • Gross Floor Area

    6500 sq ft
  • Units

  • Partners

    Island Carpentry

Sustainability Achievements


  • Walkable location
  • Near public transportation
  • Sustainable landscape
  • Native plantings
  • Ecological Stormwater Management


  • Uses locally-sourced materials
  • Designed for durability
  • Designed for low maintenance
  • Low global warming potential insulation


  • Optimized for daylighting
  • Fresh air ventilation system for indoor air quality
  • Visual connection to the outdoors
  • Low-VOC finishes
  • Formaldehyde-free building
  • Contains no EPA chemicals of concern


  • Low-flow fixtures
  • Designed to maintain natural drainage patterns
  • Solar hot water system
  • Landscaping requires little water


  • Fossil fuel-free building
  • Uses renewable energy systems
  • Uses passive design strategies
  • Predicted EUI = 12
  • Actual EUI = 8
  • R-6 windows
  • R-45 walls
  • R-60 roof
  • R-20 slab
  • Net zero
  • Fresh air ventilation system with heat recovery
  • Super-insulated
  • Triple-glazed windows
  • High Quality Air-tight construction: 0.9 ACH50