Energy Efficiency in Buildings

The Energy Efficiency in Buildings Theme is led by Prof David Jenkins at Heriot-Watt University. Through their construction and operational lifetime, buildings in the UK are responsible for 50% of all our carbon emissions. ETP universities are working with the construction industry to significantly reduce energy usage and carbon emissions by improving energy efficiency. 

Following the 2003 Energy Performance in Buildings Directive (EPBD), the role of Energy Performance Certificates (EPC) in low-energy building regulation has been highly visible in characterising the energy efficiency of our building stock. It can be argued that this has been reasonably successful over the last 18 years, driving and supporting energy efficiency programmes across Europe. However, in that time, change has occurred in the types of technology installed in homes, the ambition of carbon targets themselves, and the simulation tools available to understand energy demand in the built environment in more detail. With the growing presence of EPCs in mandatory action for new and existing buildings (in both Scottish and UK Government policy), it is vital to understand how energy compliance frameworks can and should evolve for new challenges and opportunities, with the overarching driver of a net zero building stock.

Buildings such as galleries, libraries, museums, and pharmaceutical plants are often energy-intensive, as their service plants operates 24/7 and with tight control for the indoor temperature and humidity to meet the need of collection care. These buildings are often old with high cultural values and listed for conservation. This results in the restriction of many common, effective low energy/carbon solutions. Optimised control often becomes the main option to reduce energy consumption and carbon emissions. This is a new generation of control system for high quality environmental services and energy efficiency based on a smart decision-making engine running on special programs built in Building Management Systems. Developed by Artificial Intelligence methods, such as machine learning and Artificial Neural Network modelling, these programs analyse historical data, simulate system operation, and can predict environmental conditions and energy use. This smart control focus at special-purpose institutional buildings, where close control of indoor moisture and temperature is critical is of prime concern in the operation of many organisations.

The age of “Big Data”, alongside new control technologies for buildings, has resulted in different opportunities for how our buildings are controlled, particularly with respect to energy use. Smart meters, smart appliances, intelligent Building Management Systems, thermal and battery storage, and next-generation heating technologies collectively provide flexibility to how we satisfy the internal conditions of a building whilst meeting external requirements of energy suppliers and the wider energy system. Future low-carbon buildings within low-carbon energy systems will have to be “smart”, monitoring and morphing the demand of those buildings to meet the needs of various cost, power, and carbon triggers.

The problem of the energy, comfort, and carbon performance gap (between design intentions and real-world conditions) of our buildings is well known. As our buildings become ever more complex in design and expectations, the gap continues to grow. Furthermore, the unintended consequences of design decisions become apparent only when buildings are occupied. This is further exacerbated by the changing climate, which places additional climate burdens on buildings, including overheating that leads to higher energy use, poorer thermal comfort, and greater carbon emissions. Real-world performance data and user-centred experiential evaluation are needed to improve the actual performance of our building stock. There is also a need to map, monitor, and model the changing climatic context in which our buildings are cited, especially in urban areas, to enhance their climate and carbon resilience.

In the context of existing buildings in Scotland, there are outstanding examples that are characteristic depictions of our society, culture, and heritage. Existing buildings play a big part in the fabric of our cities, particularly when net-zero targets are on the horizon and the consequences of climate change are ever so evident. Climate change-imposed dangers and recent effects can be evident in many of our heritage grandeur buildings, but equally important are the more typical buildings occupied by households potentially under threat (tenements and others). Our historic buildings require assertive solutions to repair and maintain their function and integrity without damaging their historic value. Research and data-gathering on the current state and evident detrimental dangers are required, as well as an understanding of its intended future use and hydrothermal behaviour. Equally important is maintaining its role on the city-wide landscape, preparing for a more dynamic user behaviour considering technological advances, new materials, and the evolving climate. 

To mitigate the dangers of climate change and rising energy costs, appropriate solutions must be applied to existing buildings that can be akin to the original fabric of the building but equally contribute to the reduction of energy demand and its associated carbon emissions. Retrofit interventions that are adequately associated with the building type and use should be researched, both for particular problems and building types but also as a wider rollout to solve the city-wide intentions of net-zero performance. Work on new materials that are sympathetic to the building archetype, age, and intended use are required, particularly with a view to its whole-life carbon approach. Intended demonstration of as-built solutions in combination with material science and improvement of existing products require further research academic groups and industry.

Reaching net zero target by 2045/2050 will see the phasing out of the widely used gas boilers. Most of gas boilers are expected to be replaced by heat pumps and low carbon heat network. The emerging standards for heat networks are 4th and 5th Generation District Heating (4GDH and 5GDH). These new standards, as well as heat pumps, are efficient at reduced operating temperatures, with typical flow and return temperature of 55°C/25°C. As buildings in the UK have been designed to operate at 82°C/71°C, the successful rollout of these new sources of heat relies on the ability of existing buildings to use reduced temperatures. All buildings should be “Low Temperature Ready” and this involves action on energy efficiency, controls, fault and malfunction detection, occupant behaviour, and the development of new Key Performance Indicators (KPI) for heat invoicing to incentivise occupant to provide a low return temperature

The use of building physics to estimate the performance of buildings has been in place for decades. However, whilst the laws of thermodynamics do not change, the ability of software (and hardware) to run simulations of increased complexity continues to move forward. Whether running detailed simulations of individual buildings, providing design and performance advice for building systems, or large multi-building simulations for entire communities, building simulation continues to play a key role in the design of low-carbon built environment. The growing use of building simulation with real building and energy data, and how theoretical models can inform real case-studies through “digital twin” approaches, shows how important these techniques can be even (or especially) when provided with a rich data landscape of real building performance.