This blog is part of our Net Zero series for World Green Building Week 2017 – read more here.
As part of the World Green Building Week 2017 theme #OurHeroisZero, this blog explores the opportunities and considerations for on-site renewables in the wider context of net zero energy buildings.
What are net zero energy buildings?
Net zero energy buildings can be defined in many ways, but on a simple level, it is a building connected to the grid where the energy generation matches energy consumption and balanced out to net zero. Net zero is usually assessed at the annual level, but it is becoming increasingly common to account for finer timescales in calculations to improve analyses to inform decision-making. This can be achieved by finding opportunities at all phases of the building life-cycle from construction materials at the design stage, reduction in energy consumption during operation, implementation of efficiency measures and incorporating renewable energy systems.A building connected to the grid where the energy generation matches energy consumption and balanced out to net zeroClick To Tweet
What are the opportunities for on-site renewable technologies to help achieve net zero energy buildings?
Alongside design, construction, building management factors and small-scale retrofitting such as efficient lighting, on-site renewables have also played a key role in achieving net zero energy for building energy generation and operation. On-site renewable energy generation have helped to harness clean energy, improve efficiencies and reduce dependency on the energy grid.On-site renewable energy generation have helped to harness clean energy, improve efficiencies and reduce dependency on the energy grid.Click To Tweet
On-site renewable energy is a popular approach as the energy generated can be used to offset the actual energy use of the building and can even be integrated as part of sustainable building envelope design. It is not possible to strive for net zero at the design phase only, as net zero energy must be realised through on-going operation and maintenance throughout the building life cycle.
The technologies and mechanisms available are:
- Solar Photovoltaics (Solar PV)
- Purchase of green energy from the grid
- Micro heat and power generation systems
- Wind turbines
- Energy storage technologies (battery and heat storage solutions)
More advanced approaches are:
- DC microgrids
- Smart grid and digital technologies
- Active facades, e.g. artificial leaf technologies
Solar PV and Systems Integration
Solar PV is becoming a more viable option because of decreasing costs of materials and maturity in the marketplace. The mature status of the key solar technologies makes them key players in the energy world. According to the IEA’s Technology Roadmap for Solar Photovoltaic Energy (2014), it is projected that solar power could generate 22% of the world’s electricity by 2050. Solar energy is therefore a viable contender for energy and CO2 mitigation. Solar PV is also more versatile due its multi-disciplinary approach and scalability. In comparison, micro-heat and power generation is less scalable and wind energy through turbines are usually applied as off-site renewables.It's projected that solar could generate 22% of world’s electricity by 2050 making it a contender for CO2 mitigationClick To Tweet
Of course, climate and locational factors have roles to play in determining the level of renewable energy generating capacities as well as cost and scalability. On-site renewables are however most effective when technologies are coupled together into a system to create a smart on-site renewables DC microgrid, with the application of energy storage and digital technologies. This can prove to be effective for local energy management, as well as scaling up net-zero energy buildings from the single building to the regional scale.
Solar PV as Design
In terms of sustainable building envelope design, there is an opportunity for integration into buildings materials, such as rooftops and facades. Solar PV has been especially popular due to its versatility as in the case of building integrated PV. As well as being decorative and architectural interests, innovative designs can make construction materials more productive and cost-effective compared to traditional building materials. Another element of building design is comfort for occupants which is linked to the wider issue of health & wellbeing as a value indicator for buildings.
What are the considerations for on-site renewable technologies to help achieve net zero energy buildings?
Market incentivisation is key to paving the way for net-zero energy buildings. This boils down to more cost-effective design and construction. Falling costs of renewable energy technologies have helped to increase the use of on-site renewable energy. Increasing digital technologies can help to align tariffs to real-time pricing strategies.
Balancing Loads and interactions with the wider power grid
For building energy management, there always the need to link power generation to building loads. Opportunities can be gained from balancing supply and demand to optimise performance in terms of energy and costs. On top of this, the peak load times and peak consumption reduction prospects must also be considered, as well as interactions with the wider power grid. Digital technology is creating ways to optimise and adjust demand and supply in real-time which improves energy security from outages, systems integration, reducing operation and maintenance costs.
Scaling it up!
Net zero energy buildings should be viewed at both the local and regional scale since net-zero could be achieved at the single building level, but also with the wider energy grid which is becoming smarter with the application of the smart grid. With more digital data available, it is becoming increasingly possible to use this to inform decision-making.
Holistic approach of design, construction and operation
There is a common view that most opportunities will be achieved at the building design stage. This must however be integrated into the operation of the building and integrated across the building life cycle. This is where on-site renewables present an opportunity for energy generation. A joined-up view must be taken for net-zero energy buildings. This is because a building may be designed to be net-zero, but building operation is the challenge when it comes to energy performance despite the intention at design phase and lead to deviations between modelled vs. actual energy performance.
The role of systems thinking can be appreciated within the contexts of energy management, technological developments, economics and policy. Advances and trends in energy storage technology in the microgrid have opened opportunities for net zero buildings and on-site renewable energy generation. For grid and microgrid management, a mismatch of supply and demand is an issue, however this is being resolved by energy storage. For net zero energy buildings to be realised, a coupling between technologies, systems, solutions as well as an eye for scale is required. This can be achieved by finding opportunities at all phases of the building life-cycle from construction materials at the design stage, reduction in energy consumption during operation and implementation of efficiency measures and incorporating renewable energy systems. It is not possible to strive for net zero at the design phase only, as net zero energy can be realised through on-going operation and maintenance.For net zero energy buildings to be realised, a coupling between of technologies, systems, solutions as well as an eye for scale is requiredClick To Tweet