Energy
Building a home with renewable energy: wind and solar
Renewable energy is becoming increasingly widespread, and more and more people are installing panels at home, whether as part of a renovation or the construction of a new home. But how do you build a home with renewable energy? What energy sources can we use?
This is a complex topic and depends on each project and each person (their needs, budget, and lifestyle).
For this reason, today we will focus exclusively on wind turbines and solar panels, two essential technologies for generating electricity.
But before we look at them in detail, let us clarify some key concepts.
Renewable energy sources for a home
The main source for building a home with renewable energy is the sun, but we can also obtain energy from wind or rainwater. While these are not available as continuously as the sun, in the case of water it can be stored for use throughout the year; and in the case of wind, in self-sufficient homes disconnected from the grid, the energy captured by turbines on windy days can be stored in batteries.
In any case, all these sources can always be backed up by an emergency system using storable fossil fuel, such as a gas boiler.
Cost of a renewable energy installation
It is known that the cost of photovoltaic modules tends to fall by 20% each time cumulative sales volume doubles, which in practice means that every ten years the cost of a renewable energy installation is halved.
In addition, the technology improves every year, and the profitability and payback of the panels continue to increase.
When it comes to electricity, today, with an area no larger than the roof of a 100 m2 home, we can cover the needs of a household of four with 4–5 kW of power.
This is tight, as conventional homes typically operate at an average of 6–10 kW, but we must bear in mind that the first rule of sustainability is reducing consumption. This is achieved through efficient appliances and low-consumption heating systems such as heat recovery. In any case, as we have mentioned, we can always have an additional emergency system for occasional situations in which we need a higher electricity supply, such as when family members visit.
In addition, building a home with renewable energy allows us to be self-sufficient and stop depending on fluctuations in fuel prices such as gas, or on electricity prices.
Designing a home with renewable energy
Building a home with renewable energy requires the involvement of a technician or an engineer who specialises in this area.
In our practice, although as architects we have a general understanding of all the possibilities and types of installation, we always rely on the support of an MEP specialist who is fully up to date with the latest advances in the sector and is responsible for calculating demand and sizing the required systems in line with the client’s budget.
The design of an installation of this type considers how the home operates as a whole. Not all clients want a fully off-grid home, as this generally requires a certain level of involvement and maintenance of the systems.
In the case of passive homes, where we have high levels of insulation—a key factor in reducing energy demand—heating demand can be addressed with a simple ventilation system with heat recovery, which recovers heat from indoor air to warm the cold air coming in. This system is very cost-effective and has an electricity consumption of around 10% compared to a conventional home.
Let us look in detail at each of the possible sources for building a home with renewable energy. In this case, we will consider only systems for generating electricity.
Installing photovoltaic panels
Photovoltaic panels convert sunlight into electricity. They require minimal maintenance and have a service life of around 25 years or more.
These panels can be installed in urban or rural areas, with the only requirement being sun exposure for at least 60% of daylight hours.
A photovoltaic panel produces no noise and is relatively light, so it can be installed on any type of roof.
Solar cells can be monocrystalline, polycrystalline, or film-type, depending on the requirements of the installation. In this regard, the collaboration of an expert will be necessary to help us select the type of panels best suited to our home.
Wind generators
Building a home with renewable energy from wind is possible using wind turbines installed on the roof. This type of turbine spins thanks to the force of the wind and converts that energy into electricity.
As with photovoltaic panels, turbines come in a wide variety of models and sizes, so they can be installed on any type of roof—pitched, flat, walkable, or not.
The most common orientation is towards the prevailing wind direction, although there are also turbines that automatically orient themselves depending on the wind each day.
In the case of large turbines, these are used only in rural areas where the property allows the installation of a freestanding turbine. As they are larger, they generate a greater amount of energy.
In the case of smaller turbines used on residential roofs, whether urban or rural, the system is usually connected to a battery storage pack.
A good option is to combine wind generators with a photovoltaic panel system. In this way, in summer, when solar gains are higher, the panels will perform better, while in winter they will be supported by energy generation from turbines.
The key factor in building a home with renewable energy
Building a home with renewable energy basically depends on how effectively energy consumption is reduced. If our consumption is very high, we will need a large amount of production, and that will never be efficient.
How can energy consumption be reduced?
A good recommendation is to limit the use of appliances that require a large amount of electricity to operate, such as microwaves, electric heaters, tumble dryers, air-conditioning units, vacuum cleaners, or hair dryers.
Other essential appliances such as the fridge, freezer, or washing machine should be A++ rated, as these have lower consumption.
LED lighting, although its health impact has been questioned, is more efficient and involves lower consumption than conventional lighting.
It is necessary to take into account the “standby” mode of all household devices such as televisions or computers, which together add up to a not insignificant level of consumption when we are talking about a self-sufficient home.
And a final recommendation would be to avoid using appliances simultaneously; for example, we can run the washing machine in the morning and the dishwasher at night.
Taking all this into account, we can disconnect from the grid using only renewable energy sources and reducing our energy consumption to zero.