Green energy has moved centre stage in the construction industry as home builders and construction firms look to cut carbon footprints and, in many cases, aim for zero-emissions developments. The goal of achieving low- and zero-carbon buildings has been made possible by advances in a range of technologies that rely on smart solutions and high-performance materials. Heating, ventilation and air-conditioning combines both of these areas and plays an essential part in the green building movement.
Out with the old fuels
Traditional fuels such as oil, coal, and gas are important sources of electricity generation – in the United States, they account for more than 61 percent of the country’s generating capacity. As we well know, traditional fuels, such as oil and coal, also produce pollution and greenhouse gases and consume dwindling natural resources. In the U.S., about one in every 25 deaths happens prematurely because of exposure to air pollution. It’s estimated that dirty air kills some 110,000 Americans every year – more than all road accidents and fatal shootings together. Commercial and residential buildings in the United States account for 40% of America’s total energy consumption. And according to Green Technology Magazine, heating and cooling are the most significant energy uses in these buildings.
Introducing green technologies
So clearly, there are major disadvantages to traditional carbon fuels in terms of the environmental and human cost of using dirty, polluting energy sources. Introducing green technologies does much more, though, than simply reducing your carbon footprint. The U.S. Green Buildings Council says adopting green technologies results in benefits that businesses cannot afford to ignore. Its ‘Leadership in Energy and Environmental Design’ scheme is the most widely used green building rating system in the world.
One of the biggest benefits of adopting a green approach is saving money by reducing energy bills. For instance, the USGBC estimates that LEED-certified buildings from 2015-2018 realised a total of $1.2 Billion in energy savings. Changes to heating, ventilation, insulation, and lighting can cut a firm’s monthly operational cost or a homeowner’s outgoings.
One possible HVAC improvement that can be introduced is heat recovery ventilation. The best heat recovery ventilators boast a 90 percent recovery of the heat generated in a building. That represents a substantial saving compared to buildings without heat recovery systems, where the investment in warming air is lost when a window is opened and the hot air released into the outside environment.
Build back better
As governments and organisations across the globe begin repairing the economic damage caused by COVID-19, the world finds itself in an unprecedented position. The U.S., Europe, the Middle East, Asia and Africa are injecting vast sums of money into schemes aimed at breathing life into hard-hit businesses and developing projects that will create much-needed employment.
It’s at this point we should pause and look at the goals of this funding – because never before have so many resources been amassed to stimulate growth. There are many voices calling for funding schemes to ‘build back better’. Eurovent wants the European Union to set aside some of its €1.8 trillion coronavirus recovery fund and budget for an ambitious green package that focuses on renovating the bloc‘s building stock and modernising the energy system. The organisation says this would help the HVAC industry recover from the immediate crisis and unlock the sector’s potential to future-proof the EU economy in the long run.
HVAC’s energy-saving role
There are two areas where HVAC plays an essential role in reducing energy costs and cutting carbon footprints. These are heat recovery ventilation (HRV) and energy recovery ventilation (ERV). They both bring fresh air into your home without letting the heat escape but they work in slightly different ways.
How heat recovery ventilators work
Recently-constructed buildings conform to much higher technical standards than those built 20 or 30 years ago. They have far better energy efficiency, with improved heat insulation – and they are significantly more airtight so that they retain the heat generated within a building for much longer.
This presents a challenge because new buildings need regular flows of new air to keep them healthy. Homes, for example, produce, large quantities of water vapour through the use of showers, baths, dishwashers, washing machines, and clothes dryers. Without new, fresh air problems such as mildew, mould and dust mites will occur, along with an increased risk to asthma sufferers. You’ll also find a build of odours and cooking smells if the air in a modern building isn’t changed.
The old fashioned way of dealing with these issues was to open a window, but this wastes the money spent on heating the property. Heat recovery ventilation provides an energy-efficient answer to this challenge. HRV systems are made-up of external ducting that draws cool, fresh air from outside across a device, known as a heat exchanger. It allows outgoing air to pass almost all of its heat to the incoming air without mixing the two airstreams. The incoming air, warmed by the outflowing air, then passes through the building, heating it and at the same time gathering odours, cooking smells and water vapour. This out-going airstream is then passed through the heat exchanger to warm more fresh incoming air before being expelled, along with the odours and water vapour, via exhaust ducting to the outside environment.
More benefits of heat recovery ventilators
The best of heat recovery ventilators, such as Swiss Rotors’ counterflow heat exchangers, operate with up to 90% recovery. This system allows no cross-contamination of air streams, so it is also well-suited for medical and industrial settings, where the air being moved out may contain infections and/or chemicals. Heat recovery ventilators provide a constant supply of fresh, clean air into buildings. This removes smells and indoor pollutants, keeping the people who live or work in these spaces healthy. Heat recovery ventilators cut the heating requirements of a building, reducing your heating bills. The compact nature of HRV units makes them versatile in their use around a building. In homes they can be installed, or ‘hidden away’, in spaces ranging from attics to basements or garages.
Making the most of moisture
Energy recovery ventilation works in a similar way to HRVs but goes a little further by transferring some of the moisture from the outgoing air into the fresh incoming air. This action maintains a constant humidity level and is essential if you don’t want a building becoming too dry. Swiss Rotors monolith energy recovery wheels work by passing exhaust and fresh air supplies through a wheel matrix in opposite directions. This transfers the energy from the exhaust air to the wheel matrix, and on to the incoming air.
The Swiss Rotors system operates an alternating airflow direction, which provides a self-cleaning mechanism, and makes it frost-resistant in low temperatures. The Energy Recovery Wheels are manufactured in a range of diameters, from 500mm to 2400mm, to match a wide range of applications. ERV systems are better suited for more humid climates. This is because they will restrict the amount of moisture entering your building. This, in turn, will reduce the loads carried by your air-conditioning unit, saving on operating and maintenance costs as a result.
The moisture handling process is reversible. This means that in cold winter regions energy recovery ventilators can transfer moisture from extracted air to the incoming airstream, adjusting this to a suitable level. These systems are ideally suited to properties that are too dry in the winter and/or too humid in the summer.
What’s best for you: heat recovery ventilator or an energy recovery ventilator?
Heat recovery ventilators and energy recovery ventilators share many of the same benefits. They provide you with a warm, well-ventilated space and stop you “throwing money away” into the atmosphere every time you open a window.
The chief difference between these systems is that the heat recovery ventilator only transfers the temperature of the outgoing air to the incoming air. But air always carries moisture that also holds the energy required to maintain it as a vapour. Energy recovery ventilation transfers the heat between outgoing and incoming airstreams – and a substantial amount of the water vapour between the two air supplies. Buildings in many climates will not need systems to capture water vapour because the incoming air is within acceptable moisture levels.
But homes, hospitals and offices in arid climates will benefit from the additional control over humidity levels that ERV systems provide. Buildings in excessively humid areas also use energy recovery ventilation to reduce the amount of water vapour entering a space.
In both these cases, ERV systems help to tackle extreme high or low water vapour levels to provide ideal, controllable indoor humidity levels.
If you are looking to design an HRV or ERV system, our counterflow heat exchangers or energy recovery wheels may be what you need. Get in touch to learn more.
