At a daylighting event in Copenhagen this past May, WAN met Rory Bergin, Partner of Sustainable Futures at architecture practice HTA and firm believer in the power of natural lighting in residential design. Rory is part of a team working with daylight experts VELUX on a series of residential experiments across Europe called VELUX Model Home 2020.
A range of private homes have been designed in Austria, Denmark, France, Germany and the UK to undergo rigorous testing to establish the impact that sustainable design elements can have on real families. HTA has designed the two CarbonLight test homes in the UK, located in Kettering, and are analysing how two ‘typical’ families react to the highly sustainable designs through data analysis.
This is no ordinary experiment. For VELUX and HTA, sustainability goes far beyond energy demands to factors such as air quality and daylighting, looking to inspire the temporary occupants of the houses to make small changes in their lives outside the home towards a healthier, more sustainable lifestyle. The families may have only been occupying the residences for a few months but the psychological impact of the CarbonLight Homes has clearly already begun.
Bergin notes that both children and adults are sleeping better and wake feeling more refreshed while the parents are revelling in entertainment opportunities, inviting friends over as ‘other people’s houses…now feel like caves compared to the CarbonLight Homes’. The residents have also taken steps beyond the walls of their houses, enjoying cycling and taking care to turn off light switches when leaving a room. You can read their firsthand accounts of the experiment here.
In the interview below, HTA’s Rory Bergin explains what makes experiments of this nature so important.
What was HTA’s involvement in the scheme?
HTA Design were approached by VELUX in 2008 to design two highly sustainable and unusually well-daylit homes. This was to form part of the VELUX Model Home 202 project, an initiative to explore low and zero carbon living across Europe. Other projects in this initiative have been constructed in Austria, Denmark, France and Germany. All of the projects have met a brief requiring a high daylight factor and achieving the Active House standard. HTA Architecture designed the buildings and HTA Sustainable futures developed the sustainability and energy strategy. Now that the homes are both completed and occupied, HTA Sustainable Futures are carrying out a post-occupancy study to determine how the homes are performing against the targets and how the users are responding to the experience of living in such highly sustainable homes.
What was the brief and how was it met?
The brief included a number of targets that had to be met:
-achieve a 70% reduction on CO2 emissions compared to a 2006 building (this is still being tested)
-achieve Code for Sustainable Homes Level 4 (achieved)
-aim for an average 5% daylight factor in all habitable rooms (achieved 7.5%)
-aim to achieve a Class 1 building for thermal comfort when assessed against EN 15251 (still to be evaluated)
-to influence the housebuilder market to move to better quality design
-to develop a renewable strategy that didn’t depend on photovoltaics
-to favour natural ventilation over mechanical ventilation
Why are experiments like this so important?
Experiments like this are important because they provide real information. Too many claims are made in the construction industry for performance which is never actually tested. Too many products and components are sold on the market which claim innovative performance levels but which have only been simulated or calculated and not tested.
There is constant pressure on designers and manufacturers to improve design performance, but very little pressure to prove that design performance has actually been achieved. We need to move away from thinking that because we have designed buildings which have achieved Code level 5, LEED Gold or BREEAM Excellent it means that we have created sustainable homes. It simply means that we have created buildings which would perform well if they were occupied by robots, or even better, not occupied at all. We need to be more realistic about how buildings perform in action, when occupied by real people and not base our ambitions on how they perform in simulations.
Which countries are leading the way in sustainable residential design?
The Scandinavian and northern European countries are leading the field in terms of basic building energy efficiency. Their winters are harsher than ours in the UK so there is some justification for this.
But I think that the UK is leading in the thinking about the wider implications of sustainability. Energy is only one of many issues that we need to consider in sustainable design. The code for Sustainable Homes has set a good benchmark for a wider consideration of sustainable residential development. Other standards, like Passivhaus have a very narrow focus on energy, but the Code covers a much wider scope but can be too prescriptive.
Using the Active House Specification on the CarbonLight Homes experiment has been interesting as it is a self-assessment standard and it focuses on outcomes such as daylight, CO2 pollution, air quality, and other measures which must be assessed after occupation. The ActiveHouse specification is owned and managed by an alliance of industry partners including manufacturers, contractors and designers.
What feedback have you had from residents so far?
We have had very positive feedback from both sets of residents, particularly relating to the very high levels of daylight in the homes. Both families compare them very favourable to their previous homes which were much darker. They now say that high daylight levels is something that they would look for in a new home where previously they wouldn’t have thought that this was particularly important.
The Glazebrooks, the family in the 4 Bed, prefer to invite their friends to come and visit them rather than going to other people’s house which they say, now feel like caves compared to the CarbonLight Homes. They also say that they and their children are sleeping better since they moved in and wake feeling more refreshed. Their one design complaint is that the crisp glass staircases are impossible to keep clean with small sticky children in the house!
What results are you predicting and how do the results so far compare to those predictions?
The daylight factor achieved is an average of 7.5% compared to a designed intent of 5%. We are predicting that the houses will be more efficient than a 2006 dwelling by around 70%. This makes them a good example of how to achieve the 2016 Zero Carbon standard. We have already funded domestic retrofit works by Kettering Borough council as an example of how an ‘allowable solution’ could work.
The very long and cold winter means that the energy figures so far are higher than expected. But we will ‘normalise’ them by comparing them to a normal winter and see how the performance changes. We are also doing some work with social scientists to develop tools which may help to guide designers of sustainable homes towards strategies that are more likely to provoke a favourable response from occupants.