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Further Inc.'s R-951 Residence - Passive House/Net Zero Multifamily Building


Further, Inc. for R-951

Three talented individuals with a collective 60 years of experience in eco-friendly design joined together to create an innovative, ultra-efficient residential structure. Further, Inc. is an exceptional combination of professional expertise resulting in the first multifamily housing certified as both Passive House and Net Zero in Brooklyn. The three-unit condominium in the Prospect Heights neighborhood reached new levels for high-performance as the builders had to meet stringent insulation and efficiency standards. Further, Inc. opted for an insulated concrete form system due to superior quality as well as state-of-the-art R-9 Tilt and Turn windows. The team also installed Energy Recovery Ventilation and used ductless mini-split air source heat pump systems to efficiently heat and cool the units. The rigorous Passive House standards achieved for this project provide the residence with non-energy benefits as well, including daylighting, optimal indoor air quality, and an exceptionally quiet space, which is unique for that area. Additionally, the building gained extensive free publicity offsetting marketing costs and all three units sold at a higher price point than comparable sized conventional units. The project won five awards, clearly demonstrating that the transition to multifamily net zero residences is now an achievable reality.


Project Team Profile

The R-951 Residence is the first project for Further, Inc.—a partnership that brings together three individuals with a combined 60 years of experience in environmentally friendly design. Ray Sage, Wendy Brawer, and Paul Castrucci seized the opportunity to create a high-performance new construction three-unit condominium project in Prospect Heights, an active Brooklyn neighborhood. R-951 is the city’s first building to achieve both passive house certification and net zero energy performance. While a passive house is an ultra-low energy building, a net zero building is one that produces as much energy from renewable resources as it uses over the course of one year.

Further, Inc. has been widely recognized for its work for making energy sustainability a reality. The project has won a number of awards, including a NYSERDA Trailblazer Award, the AIANY COTE Townhouse Award, the Building Brooklyn Award, and an award for multifamily housing at the National Passive House building competition.

Paul A. Castrucci is a leading passive house architect and community advocate devoted to providing clients with innovative design solutions that integrate the firm’s preeminent expertise in sustainable design. Paul's full Biography Link opens in new window - close new window to return to this page.

Eco-designer and social innovator, Wendy Brawer, is best known as the founder and director of Green Map System. Wendy has been an early advocate for energy efficiency, waste reduction, and other important issues affecting New Yorkers. Wendy continues to be actively involved in helping New York City reduce its energy consumption through diverse and unique projects. Wendy’s full BiographyLink opens in new window - close new window to return to this page.

Working in New York City for more than 20 years, Ray Sage is a contractor and consultant with a deep interest in energy efficiency and renewable energy. Ray has worked on a large array of residential and commercial projects and is also involved with activities promoting biodiversity, such as beekeeping.

Builder Team:

Building a net zero energy home is a team effort. The names and contact information for the Further, Inc. net zero team are:


Further, Inc.

Wendy Brawer 917-217-1054


Paul Castrucci Architects

Paul Castrucci (212) 254-7060


Integral Building & Design

Pasquale Strocchia

(845) 255-0418



Integral Building & Design

Pasquale Strocchia

(845) 255-0418



Aeon Solar

Rob Ashmore

(888) 460-2867

Certification Requirements

The Passive House Institute U.S. (PHIUS) requires a variety of measured results to issue passive house certification. Those requirements are a demonstrated energy use level that is 50% to 75% less than that of a standard built home, low air-leakage rates, and annual and peak space-conditioning load maximums. In addition to these stringent standards, net zero certification requires that New York ENERGY STAR Certified Homes, EPA Indoor airPLUS, and US DOE Zero Energy Ready Home standards be met.

Net Zero Strategy

Starting with a passive house design is a great baseline for achieving net zero performance. Like most passive homes, R-951 incorporates a well-insulated and air-sealed shell with state-of-the-art “tilt and turn” windows. The R-20 insulated slab increases comfort and reduces the chance of condensation, which can occur during periods of high-indoor relative humidity. The foundation and above-grade walls use an Insulated Concrete Form (ICF) system, which has an insulation rating of R-21. At the exposed front and rear walls, an additional four inches of polyiso insulation add R-25, for a total rating of R-46. The German-engineered triple-pane windows have a value of R-9, and the roof has an insulation value of R-59. Meticulous detailing to prevent thermal bridges and air leaks from material and assembly intersections, coupled with the inherently tight ICF construction, results in a building with ultra-low heating and cooling loads.

To ensure air quality, Further, Inc. uses an Energy Recovery Ventilation (ERV) system that provides fresh filtered air to the occupants, while managing indoor relative humidity. The ERV system accomplishes this using an air-to-air heat exchanger, which, during the heating season, transfers heat and moisture from the warm air exhausted to the outside to an incoming stream of fresh air from the outside, without the two airstreams mixing. In the cooling season, heat is transferred from the warm fresh air drawn into the home to the cool air exhausted out of the home. The ERV system also has the capability to transfer moisture between the two airstreams, thereby keeping humidity in the home during cold, dry winters and outside the home during hot, humid summers. These efficiencies make it possible for simple ductless mini-split air source heat pump systems to serve the R-951 condominiums. This is in stark contrast to the large fossil fuel-burning boilers that are typical in buildings throughout New York City.

Further benefits of the R-951 construction are the low noise level and the overall sense of well-being the spaces provide. The tight, well-insulated building shell helps to deaden street noise and traffic sounds that are often present in a dense urban setting. Tight construction and balanced ventilation also reduce the infiltration of unwanted pollutants, such as dust, pollen, car exhaust, and odors from neighboring apartments.

Daylighting is also a feature that contributes to the occupants’ health and well-being, reducing electrical load. Paul Castrucci and the design team paid close attention to optimizing window placement to take advantage of passive lighting and solar gains. Window size, solar energy transmittance—known as the solar heat gain coefficient (SHGC)—and overhangs were selected to maximize natural daylight and take advantage of solar gains in the winter, while avoiding overheating in the summer.

As a passive house certified building (featuring a well-insulated and tight envelope, efficient ductless mini-split systems for space conditioning, energy recovery ventilation systems, heat-pump water heaters with an energy factor of 2.7, all ENERGY STAR® appliances, 99% LED lighting, and design features for passive gains) R-951 has an ultra-low energy use. The energy consumption is so reduced at R-951 that a 12.2 kW solar electric system mounted on the limited roof space generates enough energy to supply the combined annual electrical consumption of all three units. This allows R-951 to earn the distinction of being a net zero building—demonstrating that net zero energy performance is possible in urban communities.


R-951 is a unique project that capitalized on the desirability and demand in the Prospect Heights area to help secure construction funding. The project also benefited from a green-zoning density bonus available in New York City that allowed an additional 330 square feet for increased wall insulation. This, along with other incentives and offsets, made the project financially attractive for the partners. They were confident that area real estate prices would support the projected unit prices in their building.

The building uses no fossil fuels, which eliminated the need to install gas lines, boiler flues, and related piping. This allowed the project to offset additional costs associated with the superior envelope required by PHIUS standards. The ductless mini-split air source heat pump system provides occupant-controlled heating and cooling as necessary. Additionally, the walls “shared” with condominiums in adjoining buildings provided savings on insulation.

The architectural design and engineering costs were about 30% higher than for a typical building of the same size. However, a substantial part of this cost was due to the learning curve associated with this being Further, Inc.’s first passive house and net zero project. With the knowledge and experience gained through the R-951 project, estimated design and engineering costs on subsequent projects will be lower.

NYSERDA incentives and State and federal tax credits played a role in the economics of this project as well. The NYSERDA Low-rise Residential New Construction Home Builder Incentive applicable at the time of construction was $8,000 per unit, which Further, Inc. received for meeting the most rigorous tier of the program’s performance standards. The efficiency of these three units also made Further, Inc. eligible for a $2,000 Energy Efficient New Homes Federal Tax Credit per unit.* See the current Low-Rise Residential New Construction program incentive levels.

Further, Inc. and the building owners were able to benefit from incentives and tax credits available for solar electric systems as well. Participation in NYSERDA’s NY-Sun Incentive program offers a set incentive based on the size of the installed solar electric system. See the currently available NY-Sun Incentive rates. Adding a solar electric system also made the owners eligible for a 30% Federal Residential Renewable Energy Tax Credit as well as a 25% NY State Solar Energy System Equipment Tax Credit for the cost of the solar electric system.

Overall, the builders estimate that the project cost 5% more to construct than a building built to the New York City Energy Conservation Construction Code. However, the three units sold at the higher end of the price point for similarly sized properties in that area. The project also generated a substantial amount of free media attention, which reduced marketing costs

*Please note that tax credit and incentive levels may change due to market transformation trends, changing code requirements, and advancements in technology

Lessons Learned

The primary motivation behind this project was environmental stewardship. Further, Inc. chose to pursue net zero for R-951 because they wanted to demonstrate that this level of performance is possible in dense urban communities. With more passive house projects in the pipeline, they will continue to improve their designs and develop construction details and practices that are more economical without compromising quality or performance.

When asked what they might change for the next net zero/passive house project, Architect Paul Castrucci said the use of less insulation in some areas and simplify assemblies—using fewer types of materials (e.g., using spray foam in one area combined with mineral wool in the same wall), to reduce material and construction costs. More attention would be given to reducing the air infiltration between “shared” walls. Although the shared walls on the R-951 project were adequately fire stopped and sealed to pass the air-leakage tests, Castrucci believes minimizing air leakage between connected units is important. By using more liquid-applied air-sealing products, he hopes to pass air-leakage between-unit tests by a wider margin on future building projects.

The partners also plan to develop a marketing strategy specific to ground floor units to highlight the quiet living environment achieved by building to passive house standards, as street noise is an important concern when living in a dense urban area.

Homeowner Experience

The third-floor condo was recently purchased by a municipal buildings professional active in environmental causes. One of the nicest features for its residents will be the rooftop space. Partially covered by a canopy of solar panels, the sheltered patio has a great view.

Further, Inc. counsels new occupants and educates them on how to maintain the home’s systems. They provide manuals that explain controls to the ERV and heating/cooling systems, as well as how and when to change filters, etc. This makes the transition from conventional to passive house living easier for new owners.

Pictures, Plans, Materials

Governing Inspector: City of New York   

Size: 5,600 sq. ft. gross (Three (3) 1,500 sq. ft. condos)

Stories: 4            

Bedrooms: 9     

Baths: 6  

Climate Zone: 4               

Performance Features                                                   

HERS Index  :  Pre-PV: 39  Post PV: 9

Walls: Insulated Concrete Forms  −    Front and rear walls: R-value 46

  • Side walls: R-value 21

Roof: Custom flat roof and partially green/vegetated roof − R-value 59  

Foundation: Insulated concrete forms R-value 21

Slab: R-value 20

Windows: Triple-pane, Shuco “tilt n turn” from Germany, vinyl clad − U-value 0.15, (R9) SHGC 0.50 

Air sealing: Strategy − ICF, Pro Clima tape, and spray foam – 0.28 ACH50

Ventilation: Balanced Zehnder energy recovery ventilator (ERV)

Cooling: Ductless Mitsubishi mini-split air source heat pump

Heating: Passive solar and Mitsubishi mini-split air source heat pump

Hot Water: Stiebel Eltron heat pump hot water heater

Lighting: 99% LED, 1% fluorescent

ENERGY STAR-Rated Appliances: Dishwasher, clothes washer, and refrigerator (note: induction range used)

Solar: 12.2 kilowatt (total, 3 units) PV roof-mounted

Durability Strategy:  ICF construction, specifically engineered solar truss supports, solar outlet backup for outages

Water Conservation Strategy: ENERGY STAR washer, rainwater harvesting/green roof


  • New York State ENERGY STAR Certified Homes
  • PHIUS Certified


2016 Building Brooklyn Awards – 1st Place, Townhouses

2015 AIANY COTE Awards – 1st Place, Townhouses

PHIUS Passive Project Winner 2015 – 2nd Place, Multifamily

NYSERDA Trailblazer Award – NYSERDA 2015

Citation of Excellence – Brooklyn Borough President Eric L Adams, 2015