We often get consulted in relation to the best strategy to obtain the most energy efficient buildings and while the thermal dynamics and energy calculations can be quite complex, nothing compares to the amount of choice out there with respect to different products and systems available on the market. It is easy to get lost in the technical jargon and lose focus on the ultimate goal – to achieve a building that needs minimal energy to operate in the simplest and most cost effective way possible.
It is important to minimise energy demand in the first instance as this will be an ongoing, potentially increasing, and repetitive cost in the years to come – far outweighing the capital cost of implementing a fabric first approach as part of the initial investment. Its as easy as 1,2,3!
- Design – An energy efficient building starts with the basics in terms of compact design with optimised orientation of glazing in a southerly direction. Expansive complicated building forms have a relatively larger exposed surface area, therefore more potential for heat loss, and are more difficult to construct and get right on site.
- Fabric First Approach – aim to achieve the lowest possible U-Value that is practical/feasible for floors/walls/roofs keeping in mind that anything below 0.15W/m2.K is excellent. However, towards 0.10-0.12W/m2.K is futureproofing and towards the limit of where fabric U-Values will practically and feasibly go. Also opt for triple glazed low u-value windows to complete the building fabric. The building fabric is a one-time investment in your building that will reap benefits from the moment the building is occupied – saving on energy bills and maximising comfort levels. Utilising high performance insulation solutions minimises the construction build up which saves on costs such as wider foundations and maximises internal floor space. Care should be taken at design stage that all envelope junctions have been fully resolved in terms of ensuring continuity of the thermal performance, an airtightness strategy has been considered and clearly defined and that an adequate ventilation strategy has been adopted – ideally with heat recovery or a humidity sensitive option to minimise excessive ventilation heat losses
- Services – Congratulations! Having followed steps 1 and 2 you now have a building that requires minimal energy input!!! This opens up a world of options when it comes to heating and hot water provision. While oil and gas are still viable options due to the low input requirement it is important to look beyond these into heat pumps and solar panels and other forms of renewable energy, in any case there is a minimum renewable input requirement under the current Technical Guidance document.
So you can see, it’s as easy as 1,2,3! Of course it’s not that simple and there is still a lot of choice, but following this fabric first approach will ensure your building is comfortable, energy efficient and futureproofed for generations to come.