Passive Houses Are Active in Philipstown

By William Benjamin

German architect Kay Künzel discussed passive houses last Friday night (July 31), with a breeze from the river blowing through the Chapel Restoration. Around 50 people listened to him speak about the environmental importance of the “low-energy through design” movement.

“Think of a [passive] house as a thermos or a jacket,” Künzel proposed. “A thermos keeps coffee hot and lemonade cold.” It’s a way to conserve energy.

During the talk, the audience heard discouraging facts about the current state of the environment, saw graphs with German words and learned the importance of passive houses. But, what makes a house a passive house?

The technical certifications and design challenges of passive houses stem from three necessities: insulation, envelope and circulation. By creating a closed environment through an airtight interior, an energy recovery ventilator (ERV) and a seriously thick coat of insulation, passive houses can drop all energy emissions by 90 percent.

Künzel flicked through pictures from his projects in and around Germany. There were frames of laborers meticulously sealing the house with an airtight fiber, blowing cellulose insulation into walls and installing triple-pane windows. He showed slides of his passive house settlement in the Rhineland, and passive-certified restorations of 15th-century homes. A passive house can look like any other.

The presentation was the second in a regional series. The overall two-talk event was sponsored by AIA Westchester Hudson Valley, Passive House Alliance Hudson Valley, Center for the Urban River at Beczak (affiliated with Sarah Lawrence College) and Center for Sustainable Development. EAS Windows and 475 High Performance supported the first talk in Yonkers on Wednesday, July 29, and Yaro Windows did the same for the one in Cold Spring. Hors d’oeuvres and growlers from Newburg Brewing Company were provided.

James Hartford, of River Architects in Cold Spring and president of Passive House Alliance Hudson Valley, introduced Künzel and has been introducing passive houses into Philipstown since his firm began the North Street passive project at Dockside.

“The biggest challenges come from design,” Hartford said. “Emphasis is on energy reductions first; then apply the renewables. It is an investment in the solid state elements in a building — insulation, durability and design.”

Passive house experts think of everything when calculating energy intake and output. They compute body heat, toaster use, even the difference between solar heat coming through windows during summer and winter months. The goal is to minimize the loss of energy — no heat bridges, chimneys or doggy flaps. Energy circles through the ERV and not out windows or doors.

Speaking about River Architects’ North Street passive project, Hartford said: “That is the one with the calculated heating and cooling costs of $320/per year — before the photo voltaics go on. It will be truly net zero when those panels are turned on by Central Hudson.”

The house on North Street is made with cellulose insulation (from recycled cardboard), local wood and reclaimed styrene foam boards. “We avoid plastics, foam and dangerous off-gassing materials,” said Hartford. He and his colleagues are doing everything they can to do right by the environment and right by comfort.

Imagine what it must be like to live in a passive house. You are enveloped in a calculated environment, filtered air is fanned around the space, and there is no air-conditioning unit humming in your window. You can barely hear the train on the tracks, let alone a car passing on the street. After the initial costs, the house is paying you. Yet, what about the chirp of cicadas, a breath of air cutting through the house on a cool, summer evening, or sitting by the fire on a winter night?

Passive houses are the real deal when it comes to energy reduction and controlled climate. In a world with limited resources and inefficient buildings, passive houses can be a solution to reducing energy use across the globe.

River Architects are currently working on a second passive house in Cold Spring on Kemble Avenue, with others in Bedford and Ramsey, New Jersey. Despite the uninvolved name, the passive house movement is anything but. As it starts to take hold in Philipstown, Künzel’s presentation showed that passive houses are really quite active.