Energy Saving Measures

Back in the 1990, whilst combining work at Delft University of Technology and the Energy Research Centre of the Netherlands, I studied the selection of 'energy saving building components'. Research in the next 25 years has taken me in different directions, but energy efficiency has always remained a core interest.  So with the current energy crisis of 2022, what is there in this earlier work that might be of use who are trying to cope with the current high prices of energy?

The first thing that comes to mind is a general guideline that was promoted 25 years ago as the 'Trias Energetica'. Whilst old it still makes a lot of sense. It says that there are three principles to consider when making buildings energy efficient, which should be applied in the given order:

1. Reduce the need for energy. This is done by thinks like insulating the building, reducing ventilation, and making use of any heat gains available. There is a wide range of potential measures here, ranging from putting extra insulation in the loft, buying draught excluders for doors and windows, all the way to more expensive options such as the purchase of double glazing units for windows. But in general, it all comes down to prevention and trying to reduce the heating need.
2. Where you still need some energy, use renewable energy sources. Here you may think of solar panels on roof to supply electricity, or thermal solar systems that supply hot water. There are also technologies to make use of energy in the soil, ambient air or ground water. Obviously these are expensive to install but most of them reduce your need for gas, oil and other fossil fuels.
3. Where principles 1 and 2 are not enough to cover your needs, the fall-back is to use fossil fuels. However, the recommendation is to use the most efficient system you can find in order to do this with minimal use of fuels. For instance, a modern combination boiler has an efficiency of 92% or higher. 

A second thought from my research is that whilst energy use may be an important consideration, we need to be aware that the thermal performance of a building may be linked to other performance aspects. Obviously, a simple and rigorous measure to save energy is to turn of your heating system, or to shut off radiators in rooms that are not used. However, this may have unintended consequences, such as health problems for the occupants (think of asthma). So care is needed when considering this approach. Similarly, it is often recommended to insulate cavity walls - however cavity walls also play an important role in keeping moisture out of the building. The outer leaf is often wet but as long as this is separated from the inner leaf by a cavity with circulating air there is no problem. Filling the cavity with insulation material may connect the wet outer leaf with the inner leaf, leading to serious moisture problems later.

A third important issue is that savings that can be achieved by individual energy saving measures mostly depend on the context. There are leaflets and advice making the rounds that one can save £145 per year whilst reducing carbon emissions with 640 of carbon per annum by insulating cavity walls, or save £200 per year by installing a new energy efficient boiler. Obviously, these savings completely rely on the starting point. Keep in mind that there is no point in putting double glazing in a bus shelter with an open door opening. Similarly, a highly insulated loft will not help you save much energy if the walls remain uninsulated, and windows are single glazing. In general it is worth keeping in mind that windows and doors are often the building elements that have the lowest resistance to the passage of heat.

For those that have an interest int he wide range of options, below is a list of energy saving building components that I compiled back in the past. Note that some of these 'measures' are architectural in nature, such as zoning of the building, or the area of glazing. Others align with building physics and science, such as thermal insulation in walls. Yet others are more the domain of systems and services. For more details on each alternative, and how it may help increase energy efficiency, please look at other sources of information such as that of engineering societies like CIBSE, REHVA or ASHRAE.

• advanced glazing systems
• air-thightness features
• ambient heat sources
• atrium/sunspace
• aquifer
• black attic
• blinds
• building energy management system (BEMS)
• ceramic building elements
• chemical energy storage
• clerestory/skylight
• climate adaptive facade
• cogeneration unit
• combination boiler
• compact building design
• concentrating solar collector
• cooling ceiling
• daylight-responsive artificial lighting
• displacement ventilation
• district heating
• double facade
• earth storage
• energy-efficient appliances
• energy-efficient HVAC
• energy-efficient hot water system
• energy-efficient lighting
• energy pile
• evaporative cooling
• flat plate collector
• flexible workplace
• floor heating
• geothermal heat source
• glazed balcony
• heat exchanger
• heat pipe
• heat pump
• heat-absorbing glazing
• heated ceiling
• HF-lighting
• high temperature cooling
• holographic optical element
• individual control
• individual gauges
• laser-cut panel
• light shelf
• light well/light shaft
• lighting control with presence detection
• lighting row
• lowered air exchange rate
• low temperature heating
• mezzanine
• monitoring system
• moveable thermal insulation
• natural ventilation
• nocturnal ventilation
• optimized glazed area
• overhang
• photovoltaic cells/PV
• plug-in gas connector
• radiant heating
• remote storage wall
• roof pond
• shutter
• smart meter
• solar water heater
• south-facing window
• storage wall
• sun screen
• sunspace
• thermal insulation
• thermal mass
• translucent insulation material (TIM)
• Trombe wall
• ventilation with heat recovery
• water reservoir
• wind turbine
• zoning