The insulation material we are using for the SURE HOUSE is a mineral wool material known as ROXUL. This product was chosen for several reasons. The first and foremost is its ability to dry out when wet to prevent moisture and mold issues. Compared to a typical fiberglass batt insulation which does not do well once wet, mineral wool is designed to dry out before mold can grow. This is essential for an area where flooding could be an issue, but is also very important in humid climates such as New Jersey. When creating a home that is airtight and highly insulated in a humid climate, one major concern that arises is condensation inside the assemblies of the envelope. For this reason, buildings must be designed in order to control this potential moisture issue, and depending on the season, there must be a way for moisture to dry out. ROXUL insulation is the best product for mitigating these issues and for a New Jersey coastal environment, it was a no brainer.
When talking about climate change and the need to reduce emissions, living sustainably is key. So what do we mean by sustainably? While there are probably thousands of ways to define this word, the most relevant definition today is “without relying on the use of fossil fuels or other limited natural resources.” So how is the SURE HOUSE sustainable? We will use up to 90% less energy than a typical New Jersey home by adhering to the most stringent building energy standard in the world, the Passive House Standard. This low energy demand combined with our solar array will also make us a Net Zero energy user year round. Now that’s sustainable.
When most people think of a building with low-energy use they often think of the efficient technologies used such as LED lights, low-energy refrigerators or efficient dishwashers. While these things are an important part of the equation, there is no question that in climates with big temperature swings between seasons, such as the Northeast United States, the energy needed to heat and cool a building will always be its greatest single energy demand. Therefore reducing the need to heat and cool a home is the best way to cut down your overall energy consumption, and the best way to do this is to create a building that virtually eliminates the exchange of heat with the exterior climate and holds on to the energy used to condition the interior air. This is the idea behind Passive House and explains why one of the most important parts of this house is its insulation, the material that increases the thermal resistance, or R-Value of a wall, roof, or floor assembly.
In order to reach the Passive House Standard, an energy model of a building must be validated which calculates the yearly heating and cooling energy consumption based on local climate data and all of the specifics of the home. A very important part of this model is the thermal resistance or R-Value of the building envelope, the shell of the building that is in contact with both interior air on one side and exterior air on the other. These values are split up by surfaces, walls, roof, floor, windows and doors and your energy model helps you determine what values you need to hit to meet the Passive House Standard, often 1.5 to 2 times what is required by code. For the SURE HOUSE, we have designed our house to have an R-50 roof, R-37 walls, and R-30 floors. In New Jersey, code requires an R-39 Roof, R-19 walls and R-13 floors. These numbers were chosen because of the results from our energy model compared to the cost to insulate more. While insulating is cheap, there are diminishing returns the more you insulate. Therefore, going from an R-0 wall to an R-50 wall will have a much greater effect on your heating energy consumption than going from an R-50 wall to and R-100 wall.
— We are excited to have started building the SURE HOUSE in a parking lot on the campus of Stevens Institute of Technology in Hoboken New Jersey. “SURE Construction” is a subset of our PopSci blog that we’ll use to chronicle our construction process. Check back often if you want to follow our progress and get a first hand view of how a sustainable and resilient house takes shape.