A building which can generate energy more than or equal to what it consumes...and how?
Earlier NewzPepper posts might start getting erased from the site. Just in case you would have missed out on our earlier articles, we will be reposting ReferencePepper once in a while.
Shelter is one of the most basic needs of human beings. Housing solves a lot of problems that people would face if they were out in the open, like extreme weather and temperature conditions, and also provide facilities for sleeping, eating, and hygiene. However, the way housing is set up around the world causes a lot of harm to the environment. Issues like excessive energy use at homes and the continuous construction and demolition of houses have a huge impact on climate change.
Let us start from the basics first, like we always do, explaining the various terms along the article. It’s possible that some of you might be aware of a few of these terms, maybe in bits and pieces or maybe in its entirety, but it always helps when all the information is in a thread.
We keep hearing about the greenhouse gas emissions1, greenhouse gases2, greenhouse effect3, carbon footprint4 etc. So before we move any further, let’s try to briefly explain the same so that apart from understanding t’s relevance in the article, it will also help you take active participation in a conversation between serious looking bunch of people talking about any of these topics.
Greenhouse Gas emissions1 | means the emission into the earth’s atmosphere of any or various gases, especially carbon dioxide, that contribute to the greenhouse effect3 |
Greenhouse gases2 | are actually crucial for maintaining a suitable temperature for life on planet Earth. Without the Greenhouse gases our planet would be at -17 to -20 degrees Celsius. But Anthropogenic (human release of carbon dioxide) is what is contributing to an additional or enhanced greenhouse effect3. |
Greenhouse effect3 | I am sure you must have read this in school in detail. But as a refresher we will cover the basics. GreenHouse effect is the name of this process and it comes from the way a Greenhouse works. Similar to a Greenhouse which keeps the warmth of the sun inside during the night, the carbon dioxide wraps around the earth’s atmosphere to trap some of the heat and keep it warm even in the night. |
There is more to it and we know you would have been taught about near infra rays etc. but as we said we just wanted to brush up your memory before we move forward. This simple illustration above from U.S. Energy Information Administration will help refresh your memory.
Now you might think that’s a good thing and why are people complaining about excess carbon dioxide in the atmosphere? It’s not a good thing as burning fossil fuel(coal, oil etc.) releases more of these gas which are normally required, thus increasing the carbon dioxide in the atmosphere and eventually increasing the average temperature. This causes the earth to warm up more than comfortable limits for living beings and eventually our earth will be inhabitable.
I know it’s time to get back to the main article but just one more term simply explained before we move to NET ZERO ENERGY BUILDING…and that is, “carbon footprint4”.
I sometimes feel that adults make these fancy terms just to sound intelligent. “Carbon Footprint4” is nothing but the amount of Carbon dioxide released into the atmosphere as a result of the activities of an individual, Organization or Community. So next time you hear a bunch of intelligent looking adults shaking their heads discussing Carbon Footprint, don’t shy away…just jump into the conversation and surprise them. (Photo by Kristen Morith on Unsplash)
And yes after this article you would be able to stump them by advising the Carbon Footprint Discussion Group about Net Zero House they should have had.
But let me tell you first that the story ahead is a bit futuristic, especially for India, and if you plan to pressurize your parents to build their next house a Net Zero Energy one or take an oath that you will only opt for admission in a college with a Net Zero Energy Campus or take up job with a Net Zero Building Office…then hold your horses! As there are only a handful of Net Zero Energy buildings in India. India is not ready yet to roll out this initiative in full swing unlike some other countries like UK. But India is committed and very serious about getting there.
But if you can't achieve Net Zero results yet, you can certainly use most of the ideas below to reach there and contribute towards what the entire world wants to achieve.
How will a Net Zero Building help control Global warming?
Now, just Net Zero houses/ buildings will not take care of the entire problem of increasing the greenhouse effect of the planet but it will definitely help a lot. In fact, the energy supply sector (electricity, heat, and other energy) is the largest contributor to global greenhouse gas emissions, responsible for approx. 35% of total emissions. But as they say, let’s put our house in order first…literally!
Households consume 29% of global energy and contribute to 21% of resultant CO2 emissions as per United Nations study. The most energy in households is used for heating and cooling.
Photo by Jasmin Sessler on Unsplash
Back to the topic: WHAT IS A NET ZERO ENERGY BUILDING
Simply put, Net Zero Energy is state when:
Energy produced by on site renewable energy sources
=
Amount of energy used
So if a building is producing the same or more amount of energy as the entire building and occupants are consuming then you have a net zero energy Building.
And you can figure out what Net Zero House/ Housing would mean.
If a net zero energy building is one that consumes only as much renewable energy as it produces on-site, a net zero energy community, or state, is one that cleanly produces all the energy it consumes on-site, or locally.
And what is Renewable Energy again? Just in case you have not been reading our earlier articles…
As per Collins dictionary “Renewable Energy a form of energy that can be derived from a natural source, such as the sun, wind, tides, or waves, without exhausting natural resources or causing severe ecological damage”
When you see these terms, do not get confused as NZEB (Net Zero Energy Building) or ZNE (Zero Net Energy Building) mean the same thing.
HOW DOES ONE START?
This can be split into 3 phases:
DESIGN PHASE
can itself be divided into 2 parts
- ACTIVE DESIGN
- PASSIVE DESIGN
Active Design : is a structure or system that either uses or is able to produce electricity itself through the use of technologies. Active designs are straightforward and a lot of these have been in use for quite some time, especially equipments, and there has been continuous innovations to get better results. I will list down a few for you -
GRID CONNECTION: A Grid-Connected building generates electricity for use on site for the building. Excessive electricity generated beyond the requirement of the building is supplied to the grid. In the same way, in case of any additional requirement of electricity by the beyond it is able to generate, the Grid supplies the shortfall.
Solar Electric Energy: photovoltaic (PV) modules are used to that harvest energy from the sun and convert it into electrical energy. These solar modules could be on site (roof top or on a close by land. Tracking devices can be used to follow the path of the sun for maximum exposure. Roof mounted panels also act as shade hence reducing the exposure to heat for the top floor of the building
Solar Thermal Power can be used to heat water thus reducing/ending dependency on electric operated geysers/ water heaters. These are roof mounted panels Solar Thermal Energy is heat energy generated by a roof-mounted solar collection device that absorbs heat from the sun. Flat-plate collectors are the most common type, where fluid is circulated through tubing to transfer heat from the collection surface to an insulated water tank. This strategy can be used to pre-heat water from the municipal main, or well, to decrease the amount of energy needed by an on-demand water heater.
Wind Energy: Wind Power is generated using turbines or windmills to harvest wind energy to convert it into electrical energy
Passive Design : is a method used by mechanical and electrical engineers to allow a building to use the environment around it for heating and ventilation purposes. Whether it is sunlight, wind or gravity, passively designed systems are able harness these natural forces, meaning that no grid power or fuel is required for their operation.
Location: The climate and exposure of the building will have an effect eg. sun, wind, rainfall, climate. One could also decide on a location around high Geothermal activity to plan a Geothermal System5 (We will be explaining this interesting concept later in the article under Operational Stage)
Orientation: Apart from catching maximum sunlight through the solar panels, the orientation of the rooms to be away from the sun most of the day would help save energy consumption on cooling. Also ample sunlight through smart orientation or sunroofs etc. can reduce lighting consumption. Conflicting, i know, but we can leave that to the expert architects
Ventilation: is another important aspect which helps reduce dependency on appliances for cooling in case the building is a location which has more months of summer than cold period.
Landscaping: Keep maximum landscaping around for natural shade to reduce temperature. Vertical gardening is another example of keeping the walls cooler and having a beautiful external feature at the same time. It also keeps radiation levels low.
Green Roof : Terrace areas can be completely or partially covered with vegetation over a waterproof roof. Green Roofs reduce heating of top floors of the building thus reducing electricity consumption in cooling the top floors of the building.
(Photo by Noriely Fernandez Robson Denian Mateus Annie Spratt on Unsplash)
Shade: Shaded windows towards sun facing facades is another simple example, which is already in use extensively in regions with warmer climate. Intelligently designed landscaping, as mentioned above, reduces warming of the building interiors hence eventually leading to lower energy consumption on cooling through appliances.
Rainwater harvesting: Rainwater collection from roofs and other horizontal surfaces can be reused in the building for outdoor irrigation, toilet flushing etc. subject to local policies. .
Air tight: Better sealing of doors and windows also helps saving energy as they prevent the loss of hot or cool air
Photo by Kyle Cleveland on Unsplash
Passive Design is interesting as it involves creating a structure or system that uses natural energy to achieve the results for which you would otherwise have to use electricity or any non-renewable energy source.
I am sure that large windows and sunroofs must have the first thing that would have come to your mind while you were reading about Passive design must have been maximizing glass or windows to let ample sunlight in for warmth and light when required and shade up when it’s too hot or having a sunroof to get ample sunlight in the room just under the sunroof and you would have thought “this is simple! Why am I reading an entire article about it? I am as good as any architect”. But there’s a lot more architects can do and have done with the design.
Let’s have an illustration to make you understand one of the various brilliant design ideas that go into creating an efficient Passive Design for a Net Zero Building.
CONSTRUCTION PHASE
We need to take into consideration the total carbon emissions produced and released from the process of construction of the new building and from the products used in the construction of the building up to the completion of the building. This would include the extraction of all raw materials used, their manufacturing, transportation, installation, wastage, repair etc. over the entire life of the building.
According to a report by UN Environmental Program, commonly used materials for construction like steel, concrete, aluminum, and glass account for 11 percent of global CO2 emissions. Cement accounts for around 6 percent of greenhouse-gas emissions.
A few examples of using materials which have low carbon emission during their manufacturing and use:
Lower carbon concrete mixes by using fly ash, calcined clays or lower-strength concrete wherever possible |
Minimum use of carbon-intensive materials like aluminum, plastics and foam insulation |
Minimum use of carbon-intensive materials like aluminum, plastics and foam insulation |
Lower carbon alternatives like use of wood as much as possible instead of steel and concrete. Or even better choosing carbon sequestering materials6.
What are Carbon sequestering materials6? Carbon sequestration is a process of capturing and storing atmospheric carbon dioxide. One of the methods that can be used to reduce the amount of carbon dioxide in the atmosphere to help reduce global warming. Use of plant matter such as wood, cork, hemp, algae, green concrete7 etc. Cement accounts for around 6 percent of greenhouse-gas emissions. Green concrete7 is a form of eco-friendly concrete that is manufactured using waste or residual materials from different industries, and requires less energy for production.
- Reuse of materials whenever possible. Materials like brick, metals, broken concrete, or wood can be salvaged as they typically have a much lower embodied carbon footprint than newly manufactured materials, since the carbon to manufacture them has already been spent. For example, in the case of reused wood, the energy used in cutting the tree, transporting it to the factory, and producing the end product is already spent. You skipped all these steps which you would have otherwise if a fresh processed log/ plank of wood would have been used in construction.
- Use of recycled high-carbon content materials even in the case of metals like steel as new piece of steel would have embodied carbon footprint 5 times higher than recycled one.
Photo by SJ Objio on Unsplash Maarten Deckers Lucas Lenzi Karan Bhatia on Unsplash
- And of course, minimize waste. Design the structure around most commonly available standard sized materials in the market instead of designing a building structure which requires further processing of materials like wood, frames etc.
- Insulate: effective insulation leads to lower loss of energy hence reducing the energy consumption from appliances. A well insulated Building with doors and windows that shut well is half the battle won.
OPERATIONAL PHASE
Here we will primarily discuss operational stage savings related to 2 types of buildings : Commercial and Residential. Now commercial buildings also is a very broad term and commonly includes the below:
Grocery and retail shop, Malls, large format shopping and entertainment complex, Restaurants and Food retail, Hotel and lodging establishment, Office buildings, Industrial buildings, Stadiums and sports complex
But if we try to cover all of them, this article will never end. So we will narrow down the relevance to Office buildings as, India, they take up the maximum space compared to the rest. But anyways, in terms of operational savings, except for specific equipment, which may vary, depending on the kind of commercial establishment, the best practices to save energy remain the same for all.
PLAN THE RIGHT EQUIPMENT
Energy efficient technology: In addition to using renewable energy, the building should employ energy-efficient technologies such as LED lighting and efficient HVAC (Heating Ventilation and Air Conditioning) systems to reduce the amount of energy that needs to be consumed.
Think OPEX and not CAPEX
OPEX= Operational expenses & CAPEX= Capital expenditure
What we mean by this is that the energy saving equipment might be more expensive to purchase first time but will save cost by reducing energy consumption in the longer run
Air conditioning systems which consume lower energy (Inverter AC is an example I could use as you must be familiar with this)
We will be coming up shortly with an article to explain Inverter Air Conditioning system….keep reading
Buy certified electrical equipment: Power efficient systems that have star ratings significantly reduce your energy requirements. A star rated air-conditioner will use 30-70% less electricity than a non-star rated one. Similarly, there can be several other appliances and equipment that can be used in residential as well as commercial buildings. So look for the star rating sticker on the next Air conditioner, refrigerator you plan to buy.
Check your bills as and when they come: If you read your bills well, understand the ideal energy consumption of your equipments, they will narrate their story to you of use, misuse and the health of your equipments. Once you understand the pattern, it will be very easy for you to identify when things are going wrong.
Right Air conditioning/ heating system required for the room/area: Get the load calculation done before you invest in an overly robust system for the area which needs to be cooled/ heated. An oversized system will not only increase your cost to purchase but also increase your maintenance and energy cost. Though the tonnage of Air conditioning system depends on a lot of factors apart from just the size of the room (floor - top floor tends to get more heated, general climate of the location, no. of windows/ window shading, orientation, ceiling height, no. of occupants etc.) But the general thumb rule for an air conditioning unit, if you have to go by the room size, is 1 ton for a 100 square feet room, 1.5 ton for a room which measures between 140-160 square feet and so on.
LEED certification: The Leadership in Energy and Environment Design (LEED) is an internationally recognised certificate which has well-defined standards to lower energy consumption , water conservation and avoid wastes.
Maintain, care and repair: Once you have invested in the right equipment please ensure that the same are maintained. Saving money by not maintaining the equipment and/or not getting the checks done on time will not only reduce the life of the equipment but also lead to high energy consumption.
THE RIGHT TECHNOLOGY:
Hire a good Energy Auditing Agency: An energy audit on your residential/ commercial building, wether new or old, will give you potential areas of improvement. An expert will give you advice on the right equipment, flaws in the existing equipment and about any loss of energy with ways and means to prevent the same.
Smart control: The latest controls and programmable thermostats can turn the entire building area into a Smart building which turn lighting on/ off through heat and motion sensors to eliminate dependency on human beings to do the same.
Greywater Re-use: Greywater is a term used to describe water that has been used for showering, bathing and hand-washing. It sometimes includes waste water from kitchen sinks and laundry, depending on local by-laws. Greywater Re-use involves the collection and treatment of this water for use in toilet-flushing, outdoor irrigation and constructed wetlands8, reducing the overall demand for potable (drinkable) water. Drain water heat recovery can be effectively coupled with Greywater Re-use for optimal energy and resource-efficiency.
A simple diagram on the left depicting how it works. Picture courtesy: https://www.instagram.com/verecohomes/
(Constructed wetlands8: Constructed wetlands are engineered treatment systems constructed to use natural processes involving wetland vegetation, soils and microbes for wastewater treatment)
Picture courtesy: wikipedia
Geothermal system5: Geothermal technology harnesses the Earth’s heat. Just a few feet below the surface, the Earth maintains a near-constant temperature which is in contrast to the extremes of air and soil temperature depending on summer and winter extremes. Farther below the surface, the temperature increases at an average rate of approximately 1°F for every 70 feet in depth. In some regions, tectonic and volcanic activity can bring higher temperatures and pockets of superheated water and steam much closer to the surface.
Geothermal energy is considered a renewable resource. Ground source heat pumps and direct use geothermal technologies serve heating and cooling applications, while deep and enhanced geothermal technologies generally take advantage of a much deeper, higher temperature geothermal resource to generate electricity.
Though this system will only work in regions with naturally high geothermal activity, if choice of location can be an option then the Building could be constructed.
Picture courtesy: https://commons.wikimedia.org/wiki/File:Geothermal-energy.png Rxn111130
Without getting into much details, there are three main types of technologies take advantage of Earth as a heat source:
Source: US Environmental Protection Agency
AND THE MOST IMPORTANT FACTOR IN THE ENERGY SAVING EXERCISE:
is the intent to save energy and the discipline to execute. If individuals understand the importance of saving energy and half the battle is already won.
Switch off devices when not in use. Even better...unplug.
24 degrees Celsius is accepted as the most comfortable temperature and helps optimize air conditioning saving whether at work or home. So don’t push the system to 18 degrees during summers and get under a quilt….set it at 24 degrees and we promise in no time you will get used to it.
Vampire devices: Oh! And then there are these Vampire appliances which use energy even when they are switched off or not performing their primary job eg. Set top boxes, computers, printers, microwaves. I know I am again getting excited and digressing from the main subject but I just had to mention the “Vampire Appliances” …it’s such a cool term. No?
Photo by Jorge Ramirez MChe Lee Mahrous Houses Julian O'hayon Igam Ogam on Unsplash
And here’s another cool one…Reversible Ceiling Fans: These fans can be used for both cooling and heating. During warm months, apart from being used for air circulation. air is directed down air is directed down for evaporative cooling. In cooler seasons, it draws cool air from the floor towards the ceiling and pushes warm air from the ceiling down. It might not be as effective as a room heater when the temperature is really cold outside but it does help reducing energy consumption as it reduces dependency on the heaters entirely.
But there are always disadvantages or constraints in building and maintaining a Net Zero Building. The most obvious ones are the initial investment in equipment which is comparatively much higher but again it still makes sense as one ends up saving more money in the long run. Availability of renewable resources in every location could be a major challenge.
Apart from availability you can't always depend on certain renewable sources eg. generating energy through wind….the wind will blow when it has to blow.
Now that we’ve reached the end of the article, let us share some examples of sustainable architecture and Net Zero Buildings around the world
The Unisphere, Maryland, U.S.A
The building is spread across an area of 2,10,000 square feet and is the largest commercial Net Zero building in the world. The Unisphere uses a mix of:
- 3,000 Solar Panels with photovoltaic system to produce over 1 MW of power
- 52 Geothermal wells drilled more than 500 ft. into the earth.
- High-performance/ Electrochromic envelope to have increased insulation, triple paned glazing and electrochromic tinting glass, which tints more or less depending on the location of the sun, will target a 25% thermal improvement. Electrochromic glass changes tint based on a variety of factors including season, location of sun, cloud coverage, glare off adjacent structures, and tenant preference. The tint helps to reduce the amount of thermal energy entering the building.
- Earth coupled heating-cooling system: Intake air into the atrium is routed through an underground concrete labyrinth located beneath the parking garage to pre-heat or pre-cool the air. The system operates by placing the airstream in contact with the somewhat constant temperature of the earth. While the atrium will not maintain the same interior temperatures as the fully conditioned areas of the building, this strategy improves upon the outdoor ambient air conditions.
Picture courtesy: https://www.ewingcole.com/news-firmwide/
- Thermal Pool: In conjunction with the Geothermal Well system, the Thermal Pool will helps the building efficiency by lessening the load on the HVAC system. Located in the building atrium, the thermal pool also serves as a source of evaporative cooling and heat rejection.
- Natural Ventilation operates in three stages: automatic, manual and mechanical assist. When outdoor conditions permit, windows below the floor at the building perimeter and above the ceiling at the building interior will open to provide a cross flow of air. The building atrium will act as a thermal chimney, utilizing the buoyancy of warm air to induce airflows through the building. Occupants are also able to manually open windows to permit individual comfort control in the space.
- Day Light Harvesting: a thermal pool, etc., helping the building function with a no carbon footprint. The building sells more power than it buys with the help of 3,000 solar panels that surplus energy from the 1000’s of systems during the day, and sells minimum power back from the grid to the building in the evenings.
National Renewable Energy Laboratory, Colorado, U.S.A
Indira Paryavaran Bhawan, Ministry of Environment and Forest, New Delhi, India
India’s first net-zero building constructed in 2014