November 29, 1019

The challenges facing energy efficient buildings

Simon Green, Director, Green Building Design Consultants writes:

Simon Green presents at Hertford Building Group

With UK renewable energy capacity surpassing fossil fuels for the first time in 2019¹, and government plans to ban mains gas central heating systems in new homes by 2025², sustainable and energy efficient construction is fast becoming a necessity. Yet, despite all the renewable and ‘green’ technologies available, actually implementing and using them correctly is not without its challenges.

According to Imperial College London, in the past five years the amount of renewable capacity has tripled while the use of fossils fuels has fallen by a third³; a milestone that some would have considered impossible just a few years ago. Earlier this year, the UK Government announced plans to ban gas boilers from all new homes in 2025², in a bid to lower CO2 gas emissions.

Whilst these are both positive and important steps towards a more sustainable future for all, there is still a long way to go for all buildings to implement and, most importantly, use and maintain green technologies efficiently and effectively.

So, what exactly constitutes a green technology? It is basically one that reduces emissions, conserves water, reduces waste or consumes less energy, whilst providing similar results to traditional methods. There are many different forms of green technology, although the most obvious and well known are renewable energy sources, such as wind, wave/tidal, and solar.

Thermal insulation is an effective green technology, as it is possible to make significant energy savings by improving the thermal insulation values of a building, to reduce heat gains and losses, whilst improving the comfort levels. However, it must be calculated carefully to achieve the optimum level. Too much insulation can lead to overheating, and summer temperatures also need to be modelled to ensure houses don’t need mechanical ventilation or cooling to maintain acceptable room temperature. For high levels of efficiency, buildings need to be made air-tight with ventilation directed through heat exchangers. Fortunately, the ideal amount of insulation, ventilation and heat exchange a building requires can be accurately calculated using energy modelling software.

Roof mounted photovoltaic panels
Roof mounted photovoltaic (PV) panels

Equipment such as ground-source heat pumps, which extract heat from the ground beneath a property, and air-source heat pumps, which are powered by electricity (a renewable source in contrast to natural gas), also constitute a green technology. In addition, CO2 monitors in air extract ducts can be used to reduce the volume of fresh air coming into a building at times of low occupancy. LED lighting and Building Management Systems (BMS) fall into the green technology category too, as LED lights use significantly less energy than traditional light sources, and BMSs allow for heating and lighting to be switched off when they are not needed.

Interestingly, many people perceive green technology as a recent development, but they have actually been around for many decades, albeit in less overt forms. The world’s first solar power station was actually built in Egypt in 1912, to pump water from the Nile into cotton fields. With this plethora of green technologies available, why aren’t they being used more heavily in all buildings? Well the demand is certainly there. The World Green Building Trends 2016 Smart Market Report reveals that the demand for green buildings is doubling every three years4. Yet, installing green technologies does pose a number of challenges, and there are considerations that people must take into account.

First of all, there is the cost. Many people believe sustainable building to be expensive. They are partly correct, as the upfront and initial costs of using green and renewable technologies is often much higher than standard technologies. However, the rewards further down the line in terms of energy savings, are significant. Paybacks periods vary for each project, ranging from 18 months to 20 years in extreme cases, but engineers are able to forecast the payback for each technology through modelling. Modelling the effects of various green technologies allows engineers to accurately calculate the payback period and assess whether the green technology and ongoing saving is appropriate for the clients’ needs. Overall, the complete lifecycle cost of using green technologies is considerably cheaper than standard technologies.

And of course, there is also the bigger issue of the environmental cost to consider. As guardians of our planet, we have a responsibility to future generations to protect and maintain our world. Significantly reducing CO2 emissions will have an even greater impact on all of our lives, as well as saving money.

Another key challenge to the adaptation of green technologies is the available space. Air source heat pumps, for example, tend to be larger and require much more air space to operate correctly, which can prove challenging in smaller buildings or buildings with limited space. They can affect the aesthetics of a building and the surrounding areas, with equipment needing to be situated in the garden, albeit hidden behind an acoustic barrier. Green technologies also require more commissioning and maintenance than standard services, meaning people must be prepared to undertake this to ensure optimal efficiency of the technology.

Air source heat pumps
Air source heat pumps

The last, and perhaps hardest challenge that green technologies pose, is a mindset change. It is important to understand that green technologies sometimes come with compromises, compared to standard installations, which may affect quality of life.

For example, ground source heat pumps tend to operate at lower temperatures than gas powered heating systems, and will take longer to heat the building up to temperature. Hot water provided by storage heaters takes a long time to warm up and requires a recharge period once the hot water has been used, compared with a gas fired boiler which provides constant hot water. You can’t expect to take a rainfall shower several times a day, have a continual supply of hot water, and reap energy savings. However, by using a professional engineer to calculate your water loads and usage, you can have the right size hot water tank, low water-use shower heads and taps installed to suit your individual needs.

Simon Green, Director of Green Building Design Consultants, comments “Designing green buildings is not a straightforward process. Using an engineer to help guide you and accurately calculate the potential savings is a necessity, as is being fully on board with the new technologies and how to maintain them and your own lifestyle, in order to see optimal results. However, when it is done well, the results are seriously impressive, as we showed with an exemplar project at St. Augustine’s Road for the London Borough of Camden. An 1850’s 6 bedroom semi-detached house was renovated, resulting in more than an 80% reduction in CO2 emissions, proving that even Victorian housing has a huge energy saving potential.”

With electrical energy costs averaging three and a half times those of natural gas, only through planning ahead and having the correct design, installation, commissioning and maintenance of your green technologies, will you be able to lower your CO2 emissions, reduce energy usage and save money.

1. National Grid
2. Chancellor’s Spring Statement 2019
3. Imperial College London
4. World Green Building Trends 2016 Smart Market Report

For more information, contact Green Building Design Consultants on: 01992 552 111.


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