Net zero energy buildings are structures, either site-built or modular, that produce as much energy as they consume, resulting in zero additional energy required from outside sources. While defining the parameters of what makes a building net zero certified had previously been a bit hazy, the Living Building Challenge recently developed more defined criteria. With this in mind, let’s take a look at the essential design factors in every net zero energy building.
Good Design Dictates Lower Energy Needs
Good design is the start of every net zero energy building. Before considering renewable energy sources, the building needs to be constructed in a way to minimize its energy needs. Often, commercial construction design teams will evaluate thermal performance using energy analysis programs to confirm construction is as efficient as possible.
Insulation and natural ventilation also play a role in the design phase. Often, straw-bale construction is used in the walls for insulation. Straw bale can provide insulation values of R-30 to R-35. Natural ventilation helps regulate inside temperatures without consuming energy. Some designs also use earth-sheltered building concepts and strategic landscaping for summer shading.
Efficient Lighting Options
One aspect that must be considered with net zero energy design is lighting. Besides heating and cooling, lighting is the largest energy drain in a building. Natural lighting is the best way to reduce energy requirements. Efficient designs allow natural light to find its way deep into the building. Where lighting systems are needed, using motion sensors to reduce the time lights are used and LED or CFL bulbs to use less power are the best options.
While a great source of natural light, windows can also be a source of lost heat. Net zero energy buildings take advantage of double or even triple glazing — also known as double or triple pane windows. Each pane of glass is separated by air, or another gas, which will reduce the heat transfer across a building envelope.
Renewable Energy Baked Into Design
Energy efficient design and construction only go so far. The remaining energy needs must be met by using renewable energy sources. Most often, these needs are met with wind turbines and photovoltaic modules, also known as solar. In some designs, solar panels are used in place of traditional building materials, cutting overall material costs.
Net zero design is also concerned with the energy used to create the building materials used in the actual construction. Vitruvian-built pre-fabricated building panels actually save 200kg worth of heat for every kilogram of oil used in the production of the panels over the lifetime of the building.
Biomass: A Natural Heating Alternative
While not as common as solar and wind, biomass, in the form of agricultural waste or wood pellets, can be used to provide water and space heating.
To be certified as a net zero energy building, the effect of the building on its neighbors and on urban sprawl are also considerations. While few buildings currently meet all of the requirements, long-term savings and impact on our environment should make it worth consideration for every new building.