The concept of a Net Zero Energy Building (NZEB), one which produces as much energy as it uses over the course of a year, recently has been evolving from research to reality. Currently, there are only a little number of highly efficient buildings that meet the standards to be called “Net Zero”. As a result of passages in construction technologies, renewable energy systems, and academic research, creating Net Zero Energy buildings is becoming more and more possible.
Global warming and climate change are raising issues during the last couple of decades. With residential and commercial buildings being the largest energy consumers, sources are being depleted at a much faster pace in recent decades. Recent statistics show that 14% of humans are active participants to protect global warming.
As the “zero energy” and “net-zero energy” concepts are moderately new, there are not yet definitive, widely accepted zero-energy metrics. The Department of Energy (DOE) and the National Renewable Energy Laboratory (NREL) have spearheaded much of the work on net-zero energy buildings to date. NREL presents several definitions for “net-zero energy”, and they encourage building designers, owners, and operators to select the metric that nicely fits their project.
Net Zero Site Energy
Net Zero Source Energy
Net Zero Energy Costs
Net Zero Energy Emissions
Site Energy: Refers to the energy consumed and generated at a site (e.g. a building), regardless of where or how that energy originated. In a net-zero site energy building, for every unit of energy the building consumes over a year, it must generate a unit of energy.
Source Energy: refers to primary energy needed to extract and deliver energy to a site, including the energy that may be lost or wasted in the process of generation, transmission and distribution.
Most Net Zero Energy Buildings are still connected to the electric grid, allowing for the electricity produced from traditional energy sources (natural gas, electric, etc.) to be used when renewable energy generation cannot meet the building’s energy load. When, conversely, on-site energy generation exceeds the building energy requirements, the surplus energy should be exported back to the utility grid, where allowed by law.
The excess energy production offsets later periods of excess demand, resulting in net energy consumption of zero. Due to current technology and cost limitations associated with energy storage, grid connection is usually necessary to enable the Net Zero Energy balance. Differences in how utilities and jurisdictions address payment for energy that is exported from the building into the grid can impact project economics and should be carefully evaluated.
Regardless of the definition or metric used for a Net Zero Energy Building, minimizing the energy use through efficient building design should be a fundamental design criterion and the highest priority of all NZEB projects. Energy efficiency is generally the most cost-effective strategy with the highest return on investment, and maximizing efficiency opportunities before developing renewable energy plans will minimize the cost of the renewable energy projects needed. Using advanced energy analysis tools, design teams can optimize efficient designs and technologies. Energy efficiency measures include design strategies and features that reduce the demand-side loads such as high-performance envelopes, air barrier systems, daylighting, sun control and shading devices, careful selection of windows and glazing, passive solar heating, natural ventilation, and water conservation.
Once building loads are reduced, the loads should be met with efficient equipment and systems. This may include energy-efficient lighting, electric lighting controls, high-performance HVAC, and geothermal heat pumps. Energy conversion devices such as combined heat and power systems, fuel cells, and microturbines do not generate renewable energy. Instead, they convert fossils fuel energy into heat and electricity and are can be considered energy efficiency strategies.
ON-SITE RENEWABLE ENERGY
Once efficiency measures have been incorporated, the remaining energy needs can be met using renewable energy technologies. Common on-site electricity generation strategies include photovoltaics (PV), solar water heating, and wind turbines.
Renewable, on-site thermal energy can sometimes be provided by the effective use of biomass. Wood, wood pellets, agricultural waste, and similar products can be burned on-site to provide space heating, service water heating, etc. Biofuels, such as biodiesel, may also be used in concurrence with conventional fossil fuels to meet thermal loads. More background on biomass is available on the Alternative Energy page.
Priority should be given to renewable approaches that are readily obtainable, replicable, and most cost-effective. System maintenance must also be given consideration to overtime. Life-cycle cost analysis should be used to evaluate the economic merits of various systems over their usable lifetimes.
OFF-SITE RENEWABLE ENERGY
Depending on the NZE metric and guidelines used, buildings may be permitted to use energy generated off-site to compensate the energy used in a building. If space is limited, a facility owner may install dedicated wind turbines, solar collectors, etc. at a separate location. Most often, however, credit for off-site renewable generation is gained by purchasing renewable energy credits (RECs).
RECs are available from many renewable energy technologies. Large, utility-scale wind farms, solar plants, geothermal plants, and hydropower facilities generate electricity without using fossil fuels or primary energy. The costs of constructing and operating these generation facilities are often paid for by selling the “credit” for generating energy renewably (as well as selling the energy itself). The structure and market for RECs are evolving and it varies regionally.
Net Zero Energy Building principles can be applied to most types of projects, including residential, industrial, and commercial buildings in both new construction and existing buildings. A growing number of projects have been designed and constructed across the various market sectors and climate zones.
A carbon footprint approximates the whole amount of greenhouse gases (GHG) produced to, directly and indirectly, support a person’s lifestyle and activities. Carbon footprints are usually measured in equivalent tons of CO2, during the period of a year, and they can be associated with an individual, an association, a product or an event, among others.
The GHGs whose sum results in a carbon footprint can come from the production and consumption of fossil fuels, food, manufactured goods, materials, roads or transportation. And despite its importance, carbon footprints are difficult to calculate precisely due to poor knowledge and short data regarding the complicated interactions between contributing processes – including the influence of natural processes that store or release carbon dioxide.
According to WHO, a carbon footprint is a measure of the impact your activities have on the amount of carbon dioxide (CO2) produced through the burning of fossil fuels and is expressed as a weight of CO2 emissions produced in tonnes.
The GHG Protocol Corporate Accounting and Reporting Standard, which has been the first standard for estimating carbon footprint at organizational scale, helps organizations to identify, calculate, and report GHG emissions, providing specific guidelines for performing a GHG emission inventory at an organizational scale.
The GHG protocol website provides freely available electronic GHG calculators able to estimate carbon footprint associated with specific sources or sectors of the organization. In connection with the United Nations Framework Convention on Climate Change, the GHG Protocol covers the accounting of seven GHGs such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PCFs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3). The GHG Protocol not only focuses on results but also includes a deepened analysis to identify the most effective reduction opportunities.
The world’s seven billion people consume variable amounts of the planet’s resources. According to the United Nations’ predictions, the global population could reach 9.7 billion people by 2050, and over 11 billion by 2100. Growing populations drive up emissions and deplete the planet’s resources.
Increased greenhouse gas emissions have a direct impact on global warming. It accelerates climate change with disastrous effects on our planet. All of us can contribute to fighting global warming by making climate-friendly choices in our daily lives.
Understanding your carbon footprint can help limit the impact of your consumption on the environment. There are different online solutions to support you estimate your carbon footprint.
Small changes can make a big difference in the long run, for example when it comes to transportation, food, clothing, waste, etc. Here are some tips:
Consume local and seasonal products (forget strawberries in winter)
Limit meat consumption, especially beef
Select fish from sustainable fishing
Bring reusable shopping bags and avoid products with excessive plastic packaging
Make sure to buy only what you need, to avoid waste
Take good care of your clothes
Try swapping, borrowing, renting or buying second-hand
Buy responsibly-made clothes, e.g. made from recycled material or with an eco-label
Cycle or use public transport
Be smart about when and how you drive
Try the train for your next holiday
Energy and waste
Turn down the heating by 1°, it will already make a difference
Take short showers
Turn off the water while you brush your teeth or clean the dishes
Unplug your electronic equipment and don’t leave your phone on charge when the battery is already full
Don’t store unnecessary data in the cloud
Select energy-efficient products with an “A” label
Limit and recycle your waste
Carbon footprint. A measure of the total amount of greenhouse gasses released into the atmosphere as a result of an individual’s, organisation’s, or nation’s actions. It’s usually measured in tonnes of CO2e.
Greenhouse gasses (GHG). Any type of gas in the atmosphere that blocks heat from escaping. In relation to your carbon footprint and climate change, the main ones to mention are carbon dioxide, nitrous oxide, and methane.
The greenhouse effect. The process through which GHGs in the Earth’s atmosphere trap heat from the sun. Although this is a natural phenomenon that keeps the planet habitable, our GHG emissions are causing the Earth to warm up at an unnatural rate.
Climate change. A pattern of long-term change in the temperature and weather patterns either globally or regionally. Although these alterations occur naturally, man-made climate change is rapidly accelerating the pace of them.
Global warming. The rapid increase in average surface temperatures on Earth is caused by the collection of greenhouse gases in the atmosphere. It is just one element of climate change.
Fossil fuels. Natural resources that produce carbon dioxide and other greenhouse gasses when burnt. Coal, oil and natural gas are all examples.
Energy (the burning of fossil fuels) produced 36013.52 million tonnes of CO2e.
Agriculture produced 5795.51 million tonnes of CO2e.
Land-use change and forestry (altering or converting land) produced 3217.07 million tonnes of CO2e.
Industrial processes produced 2771.08 million tonnes of CO2e.
Waste produced 1560.85 million tonnes of CO2e.
1.Insulate your home
Heating your living space can be an expensive and energy-intensive process. By insulating places like your loft and walls, you can make sure your home maintains heat during the winter and stays cool in summer. It means you’ll use less energy, reducing your carbon footprint and your household bills.
2.Switch to renewables
Energy providers around the world are now offering greener tariffs. By switching to a company that provides electricity from solar, wind, or hydroelectric energy, you can reduce your household emissions and save money on your energy bills. You could even install solar panels if they’re readily available where you live.
3.Buy energy efficient
Electrical appliances are becoming more efficient by the year. What’s more, many countries now show how efficient particular products are, meaning you can make a knowledgeable choice. Whether it’s buying energy-saving light bulbs or choosing appliances with a high energy star rating, you can make your home more eco-friendly. Additionally, make sure to turn off and unplug anything you’re not using.
4.Use less water
It takes energy and resources to process and deliver water to our homes. What’s more, it’s also quite energy-intensive to heat it once it’s there. So, by using less, you can help the environment and lower your carbon footprint. Try turning off the taps when brushing your teeth, having short showers rather than baths, and only boiling the water you need.
5.Change your diet
The food we eat can have a substantial impact on the environment. For example, meat and dairy products require a lot of lands, water and energy to produce. They also create a lot of methane, a greenhouse gas. What’s more, food shipped from overseas uses a lot more resources than local produce.
By eating fewer animal products, especially red meat, (or choosing a plant-based diet) and shopping for locally sourced food, you can make a big difference. Why not support your local farmers’ market?
There is no doubt about it—climate change is real, and it’s the result of greenhouse gasses emitted from human activities. Certain natural processes, like volcanos, do emit some greenhouse gasses, but the actual amount of volcanic activity cannot account for the steep uptick in global CO2 concentrations. The pollution released by human beings doing human things, however, accounts for the spike perfectly.
Climate change is a global problem, but local actions matter. Here are a few things you can start doing at home to help make a difference.
1.Calculate Your Carbon Footprint
When your goal is reducing greenhouse gas emissions, the first thing to do is to calculate your current carbon footprint. Terrapass provides a free carbon footprint calculator to help you estimate your annual greenhouse gas emissions. Once you understand where your emissions come from, you can take measures to reduce your impact.
For every mile that you stroll, bike, carpool, or take on mass transit instead of driving, you save one pound of carbon emissions. As a bonus, walking or biking to work is a great way to get a little exercise.
3.Switch to an Electric or Hybrid Car
Don’t rush out and buy a new car if you already have a perfectly serviceable vehicle. However, if you plan on replacing your current car anyway, a fuel-efficient vehicle can make a huge dent in your carbon footprint. An improvement of just 3 miles per gallon in fuel efficiency can save you 3,000 pounds of CO2 annually. Even better, opt for a pre-owned hybrid or fuel-efficient car.
Though you might want to venture off to far-flung vacation destinations, jet fuel is a major contributor to carbon emissions. Instead of jet-setting around the world, consider taking your vacation closer to home. For every 1,600 miles of air travel you avoid, you can save 720 pounds of carbon emissions. Maybe you can take a road trip in that new electric car for maximum energy savings. If you can’t avoid flying to a remote locale, try offsetting your footprint with a program like Terrapass.
5.Switch to Renewable Energy
Power plants are the single largest source of greenhouse gasses, especially coal-burning power plants, which produce more than half the electricity in the United States. Fortunately, thanks to the deregulation of the energy industry, you have the power to choose to make a difference when choosing your energy provider. Opt for an energy provider that uses green energy sources like solar, wind, geothermal, and hydro energy. We offer green energy plans in all the markets we serve, so always consider your options when choosing your next energy provider.