Chemistry aids in zero-energy homes development

The race to zero-energy homes

09 July 2010 17:48  [Source: ICB]

Energy-efficient buildings will drive demand for polymers such as expandable polystyrene


Dow Chemical

1 Dow Structural Insulated Sheathing (SIS) on exterior walls
2 EnerWorks solar panels for water heating
3 Dow Closed Cell Rigid Spray Down & Blown-in Cellulose inside attic
4 Basement energy recovery ventilation system for mechanical ventilation); gray water heat recovery unit; Dow tongue and groove Styrofoam under basement floor); Dow PERIMATE insulation (exterior basement wall board)
5 Energy-efficient-lighting by Kichler and Juno (compact fluorescent lighting)
6 Low-emissivity Paradigm triple-pane, krypton gas windows
7 Utility meter spins backwards when solar power exceeds house demand selling power back to the utility company
8 Closed-cell rigid spray foam inside wall cavity
9 Tongue and groove Styrofoam in exterior walls
10 30-inch (76cm) overhang manages solar heat gain
11 Dow POWERHOUSE Solar Shingles
12 Photovoltaic solar panels made with Dow Corning components

Zero-energy homes no longer entail living in huts or caves. In the near future, people can live comfortably in buildings with zero net energy consumption and zero carbon emissions with the aid of chemistry, high-technology materials, and the use of renewable energy.

US-based Dow Chemical touts the use of its POWERHOUSE solar shingles, DOWTHERM heat transfer fluids, polyurethanes (PUs), coatings, adhesives, sealants and other energy-saving products in helping create the US state of Michigan's first net-zero energy home built by Cobblestone Builders.

The project, dubbed "Vision Zero", in Bay City, is expected to save $3,507/year (€2,857/year) in energy costs and avert 44,855 lb/year (20 tonnes/year) of carbon dioxide (CO2) emissions.

Citing the US Department of Energy (DoE), Dow Chemical's Mike McGaugh, general manager for Dow Building Solutions, North America, defines a net-zero energy building as a residential or commercial building that uses about 60-70% less energy than conventional buildings, with the balance of energy needs supplied by renewable technologies.

McGaugh says the Vision Zero home is proof that homeowners can now affordably enjoy the comforts of a modern home with reduced environmental impact and still be able to achieve a net-zero utility bill.

"Homeowners can typically save up to 20% of heating and cooling costs or up to 10% of total energy costs by air sealing and adding insulation in cost-effective locations such as around windows or in attics. The Vision Zero home uses a variety of energy-saving insulation, adhesives and sealants, and weather-barrier solutions products from Dow that are already used in many conventional homes," he adds.

Aside from the solar roofing shingles, other advanced alternative energy technologies incorporated in the house include a solar water heating system, a geothermal water pump to heat and cool the home, and an energy recovery ventilator. The solar components of the house will produce enough energy to supply all needed electricity, and any excess can be sold back to the local utility company.

Cobblestone also incorporated light-emitting diode light bulbs and ultra high-efficiency appliances throughout the house.

 "Lower energy demand  from your house first before installing renewable energy systems such as solar panels"
Jack Armstrong, Construction markets leader, BASF
While renewable energy is necessary to create a net-zero energy building, implementing efficiency solutions must come first to achieve maximum energy savings, says Jack Armstrong, construction markets leader for North America at German chemical giant BASF.

The company has participated in several zero-energy building projects in the US over the past few years, including a near-zero energy home in Paterson, New Jersey, and a retrofit net-zero energy demonstration home called ReVISION Vegas in Las Vegas, Nevada.

"Our mantra is reduce before you produce. You have to lower energy demand from around your house first before deciding to install renewable energy systems such as solar panels," says Armstrong. "Otherwise, the photovoltaic system installed would have to be prohibitively large and expensive."

Particularly in energy-efficient residential insulation systems, Armstrong recommends the use of Insulated Concrete Forms (ICF) with expandable polystyrene (EPS), Structurally Insulated Panel Systems (SIPs) using EPS, and/or a hybrid system with an EPS core sandwiched between concrete.

"These newer construction techniques - SIPs, hybrid and ICF - provide environmental and cost benefits, thanks to reduced heating and cooling loads over the lifetime of the home. The lifetime energy savings outweigh the higher installation costs of these systems," Armstrong adds. BASF it expects the global EPS market to grow by about 5%/year, benefiting from the growing trend towards the use of energy-efficient insulation systems.

The DoE, says that to move toward the net-zero energy goal, key building energy-efficiency principles such as air tightness, high-efficiency appliances, reflective roofs, energy-efficient fenestration, passive solar techniques, and recovery of waste heat should be applied in combination with renewable energy use.

"Advanced energy-saving technologies are indispensable to making net-zero energy houses feasible. A net-zero energy house is not a single technology but a suite of closely integrated technologies," the DoE reports.

The DoE notes that residential and commercial buildings account for around 40% of US primary energy consumption, as well as 39% of CO2, 18% of nitrogen oxides, and 55% of sulfur dioxide emissions.

In June, the DoE awarded $76m (€61m) to several US companies that included Dow, silicones producer Dow Corning, technology companies Honeywell International and 3M, chemical company Chemtura, and nanotechnology firm Applied Materials, as well as various universities and research groups to develop advanced energy-efficient building technologies and training programs for commercial building equipment technicians, building operators and energy auditors.

The projects aim to help make US buildings more energy efficient and cost effective, as well as establish a green workforce with technical expertise to reduce energy costs for consumers.

This is the first time that Dow has been able to partner with the DoE to support the development of advanced insulation products, says Bill Jackson, global research and development director for Dow Building and Construction.

The company received $3m from the DoE grant to develop next-generation insulation for high-performance, energy-efficient wall, roof, and foundation insulation systems. Dow Corning, meanwhile, received $1.2m to develop of a silicon-based high-efficiency building insulation system.

According to US-based consulting firm Lux Research, global sales of energy-saving green building materials amounted to $62bn in 2009, and are expected to reach $75bn in 2015.

Net-zero site-energy use: In this type of ZEB, the amount of energy provided by on-site renewable energy sources is equal to the amount of energy used by the building. In the US, "zero-energy building" generally refers to this type of building.

Net-zero source-energy use: This ZEB generates the same amount of energy as is used, including the energy used to transport the energy to the building, thus accounting for losses during electricity transmission. These ZEBs must generate more net electricity than net-zero site-energy buildings.

Net-zero energy emissions: Outside the US and Canada, a ZEB is generally defined as one with zero net-energy emissions, also known as a zero-carbon or zero-emissions building. The carbon emissions generated from on-site or off-site fossil fuel use are balanced by the amount of on-site renewable energy production. Other definitions include not only the carbon emissions generated by the building in use, but also those generated in the construction of the building and the embodied energy of the structure.

Net-zero cost: In this type of building, the cost of purchasing energy is balanced by income from sales of electricity to the grid of electricity generated on site. Such a status depends on how a utility credits net electricity generation and the utility rate structure the building uses.

Net off-site zero-energy use: A building may be considered a ZEB if 100% of the energy it purchases comes from renewable energy sources, even if the energy is generated off site.

Off the grid: stand-alone ZEBs that are not connected to an off-site energy utility facility. They require distributed renewable energy generation and energy storage capability.

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By: Doris de Guzman
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