All of our projects feature some level of 'eco-design' - it's essentially what we do.
However, there are a range of approaches and client requirements, from the minimum energy performance required to satisfy Building Regulations, to the 'gold standard' of Passivhaus design
Some years ago, we wrote these 'lessons for eco-design', and while technologies and energy sources change, the basic principles hold true
eco design principles
We have been practicing ‘eco-design’ since long before words like sustainability and carbon emissions were commonplace -although the details are complex, the principles of ‘green’ ‘eco’ ‘sustainable’ architecture are simple:
1 : insulation, insulation, insulation
The first principle of eco-design is to insulate as much as possible - e.g. working to the passivhaus standard requires a u-value of ± 1.0 for the major elements of the building
2 : airtightness
In recent decades the importance of good airtightness has been realised, in order to avoid draughts + control ventilation.
The passivhaus standard seeks to reduce air-loss to 0.6 ac/hr
3 : comfort ventilation [mvhr]
In order to achieve good + healthy air quality, a central mechanical ventilation system is normally used, which can be made extremely efficient by adding a heat recovery unit
4 : passive solar
We seek optimal passive solar gain, balanced with shading to avoid summer over-heating [we’ve all been fried inside conservatories in June] - passive solar depends on site, shading + orientation
We favour the widely supported ‘fabric-led’ approach, where most effort is spent on the basics of insulation, airtightness and comfort ventilation.
However, clients are increasingly drawn to the ‘active’ aspects of eco-design:
5 : active solar
Photo-voltaic + solar heating panels generate electricity + hot water respectively.
Whilst these generally have longer pay-back periods than the passive approaches, the capital costs are reducing, and solar PV installations are becoming virtually standard
6 : micro-generation
With the introduction of government subsidises via FiTs [feed-in tariffs] and RHI [Renewable Heat Initiative] the various forms of generating electricity - PV’s, wind power, hydro-electric are rapidly becoming more economically viable
7 : biomass | heat pumps | geo-thermal
Biomass [generally wood-based] heating is increasingly seen as a less sustainable and more polluting source of heating.
Heat pumps [both air-source and ground-source] have attracted huge public attention in recent years, but their efficiency and that of the building need to be carefully considered.
note: Increasingly, we are now designing all-electric buildings, using for example heat-pumps for space and water heating, in response to the rapid de-carbonisation of the national grid - almost inconceivable to eco-designers even 5 years ago