The architecture of zero carbon living

The 2018 UN Paris Agreement insisted that we must attain net greenhouse gas emissions of zero by the middle of the 21st Century. This is a huge goal to achieve, but if we want to avoid catastrophic climate change to our world, we have no choice but to succeed.

It’s now understood that our present demand for fossil fuels as our most prominent source of energy can no longer be sustained indefinitely. One of the main users of energy is the building and construction sector. The other user is ourselves and our continued operation of these structures that have been created for our needs.

Government legislation and companies who deliver sustainable technology are trying to create ways for us to construct buildings that use a lower amount of energy to create and, when used by us, need less energy to maintain. If they are successful in their ambitions, it will reduce the continuous drain on our non-renewable energy resources.

From the designers of these sustainable homes to those who live in them, there is an onus on all of us to understand not only what’s at stake but what our role is in bringing this goal to a positive conclusion. We can all make positive choices and reduce this constant demand for energy.

Zero carbon homes

Zero carbon homes pertain to housing that possesses a superior rating for energy efficiency. The aim of a zero carbon home is to result in no net release into the atmosphere of carbon dioxide that does not mean absolutely zero emissions. The homes will emit some carbon dioxide, but this should be offset by generating clean energy.

Only the emissions released during the occupancy of the building count. This means that any carbon dioxide emissions in the very materials of the home or incurred as a result of its construction are not counted.

Only the emissions from lighting, heating, cooling and ventilation are included. Emissions from plug-in appliances and those used for cooking have been excluded. The reason for this is perhaps in part to make the zero carbon status more attainable, but also because this area does not inform on the quality of the house’s performance, but rather the people who occupy its habits and behaviour.

Zero carbon homes require an exceptionally low quantity of energy to deliver the day-to-day requirements for the occupants of a family home.

Level six of the code for sustainable homes

The code was set up in the UK as a way to assess the environmental performance of homes and rate and certify them. It comprises a set of standards which are utilised in the design and development of new homes as well as their construction. Their aim is to encourage ongoing improvements in the building of sustainable housing. The buildings are assessed on a scale of six different levels. A code six would indicate an ideal example of a zero carbon house.

Reducing energy demand

The most simple and efficient method of reducing carbon dioxide emissions and creating a sustainable home is to reduce the demand for energy. This means creating or upgrading buildings to make them more energy efficient. While this can be achieved at a later date it is easier done from the outset at the design stage. Expansive southern facing windows can pull in heat and light in winter and extra thick walls that are airtight, superior levels of insulation and well-sealed windows and doors will ensure no energy is wasted. Water can be saved with low-flow plumbing taps and the use of LED bulbs is an important lighting choice.

Using renewable energy

Once the quantity of energy use has been minimised, the next step is to replace the required energy to run the home with renewable sources of energy instead. There are a variety of such sources and they are becoming increasingly more affordable.

Due to its low cost, the most popular form of renewable technology in service uses the sun’s natural heat. Solar thermal power is delivered through panels located on the roof. Warmth from the sun is used to deliver our domestic needs for hot water from showers and baths, to necessary tasks like doing the dishes or cleaning the car. Solar PV panels, which can absorb the suns energy to generate electricity, are also an option.

Biomass boilers work in a similar fashion to gas boilers but use wood pellets for fuel delivering hot water and heat to homes. Air source heat pumps are an alternative way to warm and cool homes transferring air from outside to in and vice versa.

Passivhaus technology

Passivhaus (or Passive House) technology is defined in terms of both comfort and air quality, according to the Passivhaus Institute:

“A Passivhaus is a building in which thermal comfort can be achieved solely by post-heating or post-cooling the fresh air flow required for a good indoor air quality, without the need for additional recirculation of air.”

The concept of a Passivhaus is to utilise free heat to warm homes. The gas and electrical appliances in our houses all generate heat of their own. From the larger white goods like refrigerators, washing machines and cooking equipment like ovens and microwaves, to media equipment like personal computers and televisions, they all give off free heat – even the smallest electric items like light bulbs and phone chargers. With a Passivhaus none of this byproduct energy is wasted. The free heat passes through a heat recovery ventilator it then transfers it to the incoming supply of fresh air before it exits the building.

These zero carbon homes do not usually use renewable energy sources as they are already exceptionally energy efficient.

Allowable solutions

To offer developers an economical way to attain a zero carbon standard, the government has offered allowable solutions. The developers are allowed to offset emissions in buildings where this is difficult to achieve by making an investment in renewable energy off-site or by retrofitting or upgrading the energy efficiency of other buildings.

Posted by Mark
April 16, 2019

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