The clock is ticking with the Government having set clear targets for buildings to become carbon neutral. New homes and new schools face a 2016 deadline, public sector non-dwellings need to become zero carbon by 2018 and other non-dwellings need to comply by 2019. However, despite these targets, the uptake of renewables and microgeneration is still slow with contractors and consultants failing to embrace the technology.
Fabric
So why is the building services industry dragging its heels on renewables? One reason is that renewables can be expensive, especially if they are considered just as a bolt on solution to meet a local 20% renewables target. However, reaching carbon neutral targets is not about pay back. The Government has given clear targets which it wants the construction industry to meet. It is therefore important to look at renewable energy sources holistically in order to meet the targets in a cost effective and efficient way. The first step is to consider the fabric of the building. Before a renewables technology is chosen air tightness, heat gains and the location of the building all need to be considered.
Often services in many buildings are installed to compensate for the inadequacies of the building envelope. The internal temperature of a poorly insulated building will be strongly influenced by fluctuations in external temperature, so heating and cooling is needed to mitigate that influence.
A well insulated building, on the other hand, requires much less input from energy hungry services to maintain a comfortable environment. So getting the building envelope right is the key to minimising energy consumption – before we rush headlong into selecting a clever renewables solution.
Efficiency
Once the fabric of a building has been improved so that heating and loads are greatly reduced another core area to consider is energy efficiency. With a low energy, low carbon building it is far easier and cheaper to reach the local 10 or 20% renewables target since less energy is needed. With many local authority renewables targets inspired by the ground-breaking Merton Rule it is important to note that underlying the Merton Rule the key message is as much about energy efficiency as renewables. In fact some argue that the best example of renewables is using energy efficiency measures.
Once the building envelope and its energy efficiency are addressed the next step is renewables specification. When it comes to actually selecting a renewables technology consultant, contractors are still cautious. Everyone wants a quick win with specifiers using SAP and SBEM as specification guides. However, SAP does not take into account location, which is a variable that needs to be considered in order to select the correct renewables technology for a project. For instance installing a solar thermal system in the South West would be more efficient than installing the same system in Cumbria. Meanwhile, with SBEM there are 15 weather types as well as other variables, such as wind and temperature, which means that it is easier to select an appropriate technology.
Location
The location of the project also brings into play another current renewables debate on whether to opt for onsite or offsite renewables. The majority of conurbations have very low wind profiles so there is little to be gained from installing wind turbines in a town or city. Therefore, building a large wind turbine plant in a windy location and transporting the power to buildings will give a lower cost per kWh, despite the distribution losses. However, currently some councils are still calling for local accounting, demanding that the 20% renewables targets have to be onsite rather than a cable delivering the power. This debate looks set to continue as the benefits of district heating and cooling systems near to a site are advocated as a favourable solution.
Technology
Part of the renewables problem is searching for the definitive answer to the zero carbon conundrums and selecting the right product. However, there is not just one answer. Following the development of each new technology there is hope that this will be the solution. As a result specifiers jump on the new technology only to later discover that it is not ideal for their particular project. Problems with the location of ground source heat pumps; air to air heat pumps freezing up; and wood chip boilers not working once installed; are just a few of the difficulties that have tainted the renewables name.
Although, the Government has given clear carbon neutral targets, what is now needed is practical advice on how to achieve zero carbon buildings. The building services sector needs steering on which technologies are tried and tested to help with product selection.
And as buildings become more efficient the ratio between build energy and operational energy is going to change, so the embedded energy becomes more significant and there will be less justification or demolition and new build. Instead we can anticipate reusing buildings much more – perhaps changing their function and certainly improving their energy efficiency.
All of which means we are going to have to make much more extensive use of renewable energy sources in the future. This is borne out by the UK Renewable Energy Strategy consultation document, published in June of last year. This document follows on from the Energy White Paper, which had to be modified by European targets for 15% of all energy to come from renewables by 2020. Only 20% of this is to be achieved from transportation, a figure that is likely to fall if the current concerns about biofuels are sustained, putting a significant onus on buildings to do their bit.
So there is going to be considerably more emphasis on electricity in buildings and a key role for building services engineers is to incorporate more energy generation in buildings. And while one option is to put a small nuclear reactor in every building, I think we can be pretty certain that broader use of solar photovoltaics (PVs) will be more acceptable.
In fact, some forecasts suggest that we could be deriving 50% of our electricity from PVs by 2100. For that to happen, the PVs will not only have to become more efficient, but also much cheaper to provide a sensible payback. Given that PVs are already a third of the price they were 20 years ago, and considerably more efficient, that seems eminently achievable.
In the shorter term, there will still be demand for traditional plant such as boilers and chillers, so we need to ensure these are the most efficient available and linked to efficient control systems. Regarding new technology the only certainty for consultants and contractors is that the baseline will continue to move as the Government keeps pace with environmental concerns and carbon reduction. In October the Government’s pledge to cut greenhouse gas emissions by 80% by 2050, raised the bar yet again and so drawing a line under the importance of renewables to our future energy needs. Now is the time for consultants and contractors to embrace renewable energy sources as the way forward since the carbon neutral deadlines will herald the end of traditional building services.