PART 4: LEGACY PORTFOLIO
Dial Corner Drive View
Evidence In Support Of The Premise That Dial Corner Represents The State Of-The-Art Of High Thermal Mass Buildings In The UK.
This section provides a detailed explanation of Dial Corner’s technical innovation through the buildings that have gone before. It does so by reviewing in chronological order the combined data from selected legacy buildings as one data set[see Figure 1]. By accumulating and analysing this large body of combined data, the premise that Dial Corner represents the state of the art of UK earth sheltered buildings is provided more evidence.
The following narrative derives evidence from 7 projects, representing 28 buildings, spanning 22 years. The met-analysis samples data from 4 projects, that have generated 7 million points, representing 19 buildings, over 12 years, references a 2006 PhDiii, two peer reviewed papers and the most detailed published history on the subjective .
Also relevant to this supporting evidence are the twenty-two years of designing, building, monitoring, disseminating and publishing in the field of UK high thermal mass buildings. Dial Corner’s designer has self-built three such buildings, lived in one for thirteen years and operate his Chartered Architects Practice from two, over sixteen years.
While Dial Corner may have achieved one of the highest Design SAP Ratingsvii in the UK (167A) the calculation is merely an indicator of broader more tangible performance characteristics informed by evidence based research from a significant portfolio of buildings viii. The SAP calculation is still pertinent, given it is the UK’s prevalent third party certification methodology for energy efficiency and carbon emissionsix. It could be reasonably asserted that this dwelling, if built, may become referred to as one of the most energy efficient dwellings in the country. It is a building that will readily adapt to an off-grid existence once standalone energy storage facilities advance in efficiency and reduce in cost.
All the legacy buildings listed below, including the benchmark buildings on Figure I, have been designed using passive solar design techniquesx in which thermal mass plays a significant role in tempering ambient air temperature and contributing significant passive space heating
Dial Corner West Elevation
The four cited projects below have the following in common, the same designer, a common evolving construction specification, naturally ventilated, low grade back up electric under-floor heating and all providing in-use building performance data.
The first of the projects was the home for thirteen years of Dial Corner’s designer and included an adjacent office, 89 Gedney Road, from which he operated his Chartered Architects Practice. This dwelling achieved a ‘zero heated’xii status, was naturally ventilated and optimized passive solar design techniques (xiii);
2003
87 Gedney Road, Long Sutton, Spalding, Lincs, PE12 185m2, 4 bed detached, single storey, dwelling, private residence with solar thermal SAP EPC, 88B Measured heating load 6.49kWhrs/m2/year with active thermal mass at a rate of 1.19MJ/K/m2 allied with an average U Value 0.22 W/m2K with no Air Pressure Test (APT) undertaken. APT’s were introduced to the UK Building Regulations in 2006 and became mandatory in 2010. Temperature was monitored during twelve years of occupation but with reasonably consistent recordings of internal air temperature, producing an average of 20c.
The Honingham project (xiv), was the UK’s first earth-sheltered social housing scheme and winner of the RICS International Sustainable Building of the Year 2006;
2004
21 Fellows Road, Honingham, Norfolk NR 65m2, 2 bed detached, single storey, social housing with solar thermal SAP EPC 75C
Measured heating load zero kWhrs/m2/year with active thermal mass at a rate of 1.52MJ/K/m2 allied with an average U Value 0.3 W/m2K with no Air Pressure Test (APT) undertaken. Temperature monitoring was limited to three mercury thermometers during twelve years of occupation but with reasonably consistent recordings of internal air temperature, producing an average of 210C.
2004
17 Fellows Road, Honingham, Norfolk, NR9 5BD 65m2, 2 bed end terraced, single storey, social housing with solar thermal SAP EPC 75C
Temperature monitoring over four years with consistent recordings of internal air temperature, produced an average of 20c.
Honingham’s design was informed by the experience and early monitoring of both 87 & 89 Gedney Road. Numbers 17 and 21 Fellowes Road are two of a group of four buildings, providing almost simultaneous monitoring with that of Gedney Road. All four Honingham buildings were built to the same construction specificationxv, occupied by three couples of a similar age and a widowed pensioner. Numbers 17 and 21 were occupied by two couples of a similar age. Number 17 couple were employed full time, while at 21, the husband was ambulant disabled with his wife, his full-time carer, both were at home full time.
Energy consumption across the four dwellings varied by up to 100%, while heating load variance ranged from zero heating (21) up to 22kWhrs/m2/year(17)[see Figure I] Lifestyle, behavioural patterns and attitudes to resource management where evidently disparate amongst the four households and was reflected in the variation of energy and water consumption. The water consumption of 21 achieved consistently 21Litres/person/day over the four years of monitoring.
The residents of 21 displayed a forensic approach to energy conservation and water reuse, much was learned from their performancexvi . Despite the variance amongst the households, the overall performance compared to the national average UK household data available at the time, was exceptional. The scheme was duly awarded the International 2006 RICS Sustainable Building of the Year award.
The next featured project, Unity Gardens was the UK’s first near autonomous social housing schemexvii , winner of the HCA Sustainable Social Housing Project 2010. The project generated most of its energy on a net annual basis, harvesting up to 50% of its water and managing its own waste on site.
2009
3 Unity Gardens (UG’s) Bridge Road, Long Sutton, Lincs, PE12 9FF 65m2, 2 bed detached, single storey, social housing with renewables SAP EPC 105A
Measured heating load of 11.76kWhrs/m2/year with active thermal mass at a rate of 1.0MJ/K/m2 allied with a building average U Value 0.28W/m2K and an Air Pressure test of 3.67m3 @ 50Pascals. Over three years number 3 recorded reasonably stable internal air temperatures of 210C. The lowest recorded internal air temperature of 17c and highest of 26c.
2009
4 Unity Gardens (UG’s) Bridge Road, Long Sutton, Lincs, PE 65m2, 3 bed detached, single storey, social housing with renewables SAP EPC 106A
Measured heating load of 23kWhrs/m2/year with a building average U Value 0.26W/m2K and an Air Pressure test of 3.6m3 @ 50Pascals. Recorded stable internal air temperatures of 20c with similar temperature variance as number 3.
Monitoring of Unity Gardens occurred over two consecutive years and included the first year of occupation. Generally household energy consumption reduced in the second year while internal air temperatures remained reasonably consistent. The design, unlike its architectural precedents (Gedney Road and Honingham) included SIP roofs with up to 8.5kWpeak of roof mounted photovoltaic arrays. Numbers 3 & 4 are part of a group of six earth-bunded dwellings, all six were built to the same construction specification, occupied by three young families and three couples, all adults were in either full time or part time work. Occupational patterns were similar across all households.
Energy consumption across the six dwellings varied by only 20% while heating load varied by up to 300%.
Despite the higher insulation levels (lower U Values) of UG’s than its precedents, the heating load requirements across all six dwellings was considerably higher. In the absence of recorded comparable air leakage data (APT) across the three selected schemes, it was assumed they were of a similar standard.
The observations and measurements of the three projects (12 buildings) provides a statistically significant correlation between heating loads and thermal mass. The evidence gathered appears to support the cause and effect relationship between lower heating loads in the presence of higher active thermal mass given the relative consistencies with the insulation, orientation, typology and air permeability.
As with the Honingham scheme, lifestyle, behavioural patterns and attitudes to resource management varied across the six households but less so than at Honingham. This was in part due to arranged site visits and two workshops for the UG’s residents with the residents of number 21 Fellowes Road, Honningham. The scheme was subsequently awarded the 2010 HCA Sustainable Social Housing Schemexviii award.
The development of seven offices known as Canebuzo at Hoddins Way was a joint venture with Lincolnshire County Council and its architect. The collection of fifteen buildings in Long Sutton became the largest collection of its typology in one settlement in the UK.
2010
9 Hoddins Way (9HW) Long Sutton, Spalding, Lincs, PE12 9JB 135m2 detached, single-storey, offices SBEM EPC, UK’s first A+xix , -7.8tonnesCO2/year
Measured heating load of 9.09kWhrs/m2/year with active thermal mass at a rate of 1.16MJ/K/m2 allied with a building average U Value 0.2W/m2K and an Air Pressure test of 0.94m3 @ 50Pascals. Over four years recorded stable internal air temperatures of 22.20C with a temperature variance of + or – 40C diurnally and inter-seasonally despite an external temperature variance of 570C.
Monitoring of number 9 Hoddins Way (9HW) occurred over three consecutive years using 28 in-built hardwired sensors providing data on temperature and relative humidity (in and out) energy consumption, daylight and sunlight, every 15minutes.
Core Temperature variance inter-seasonally at 9 Hoddins Way
The earth-covered design included a 5kWpeak vertical axis wind turbine for its first two years but was later removed due to inconsistencies in performance. A 4.5kWpeak roof mounted array replaced the turbine. Number 9 was the first earth- covered office built of seven on the same site Canebuzo (Carbon Neutral Business Zone) The design of 9HW deliberately sort to advance on the performances of its legacy portfolio of fourteen buildings by increasing insulation, thermal mass and reducing air leakage. The results produced the highest recorded average internal air temperature, 22.20C with the lowest temperature variance, + and – 40C and one of the lowest heating load demands 9kWhrs/m2/year.
Accumulating the large body of combined data from 9HW and fourteen other similar buildings, strengthened the evidence that there is very probably a cause and effect relationship between thermal mass and heating load demand. To demonstrate these observations, both temperature gradients and core temperatures were mapped across the building:
• Temperature Gradients
Informing a better understanding of the way in which the heat energy is stored and distributed about the building
• Core Temperatures
A closer inspection of the core temperature data reveals the extent to which the thermal mass fabric is resilient in retaining its heat energy
Those graphs strengthened the evidence that a body of heat energy is retained within the thermal mass of the building fabric sufficient to sustain elevated internal air temperatures without significant supplementary heating. This characteristic is referred to as a residual heat reservoir.
Such was the significance of the findings, a peer reviewed Paper, titled, Reservoirs of Heat: The defining characteristic of high thermal mass buildingsxx was published at the 2014 ACUUS Conference in South Korea.
9 Hoddins Way: 12 months of external and internal temperature and heating load data
The paper introduces the empirical data in support of the premise that high thermal mass buildings can significantly reduce heating loads together with concomitant green-house gas emissions. This paper also demonstrates that stable internal air temperatures are maintained with minor variations in spite of wide external air temperature variations. This building performance is achieved utilizing passive solar design techniques allied with a high thermal mass superstructure and a super- insulated fabric. These combined building design solutions create the characteristics that enable the primary heat source to be derived from solar gains, human occupation and supplementary heat gains from ancillary equipment. In turn that heat is retained in the buildings high thermal mass fabric all year round, providing a residual heat reservoir.
Viewing such buildings as reservoirs of heat energy with an active thermal core assists in understanding how to usefully employ heavy building materials for a more responsibly built environment.
The construction specification of Dial Corner includes a higher level of insulation, more thermal mass and a significantly lower air permeability than its architectural precedents.
2021
Dial Corner, London Road, Suton, 127m2 detached, single-storey, dwelling Design SAP 167A, -7.4tonnesCO2/year 20kWpeak pv’s
Anticipated heating load of <8kWhrs/m2/year with active thermal mass at a rate of 1.52MJ/K/m2 allied with a building average U Value 0.1944W/m2K and anticipated Air Pressure test of <1.0m3 @ 50Pascals. Anticipated average internal air temperature 23c.
An improvement in any one of the building performance parameters for Dial Corner would have resulted in an improved performance on its legacy portfolio. More than one aspect of the dwelling specification has been advanced. The improved specification proposed could potentially lead to the buildings heating load from supplementary heating (electric under floor heating) to zero with sustained elevated internal temperatures in the region of 23c with little diurnal variation.
A rigorous three-year post occupation monitoring project is proposed. The in-use building performance data is to be placed on a public access website, live, plus one day. By sharing the performance data in an open-access platform will disseminate the low-tech building solution to the general public at large. The project aims to demonstrate on a public platform that it is possible to design and occupy buildings without resort to fossil fuels, and without resort to mechanical devise for space heating and ventilation.
LEGACY PORTFOLIO SUMMARY
The evidence provided at the design stage of this project, demonstrates that the Dial Corner design represents the state of the art of UK high thermal mass buildings.
Dial Corner seeks to advance the known science of active thermal mass in reducing heating loads potentially to zero. Informing the design solution is a metanylsis of accumulated data from a legacy portfolio of 28 buildings, from which 7 million data points have been collected from 19 of those buildings over 12 years. That body of evidence also includes a PhD, peer reviewed papers firsthand experience of its designer in constructing, occupying, monitoring and disseminating this building typology contributing evidenced based research.
Dial Corner may become referred to as one of the most energy efficient dwellings in the country once constructed, achieving an as-built 167A EPC, possibly one of the highest ratings ever recorded by the Standard Assessment Procedure. That calculation estimates the dwelling could also mitigate carbon annually at a rate of -2.5 tonnes.
The design heating load is less than 9kWhrs/m2/year with active thermal mass at a rate of 1.52MJ/K/m2 allied with a building average U Value 0.19W/m2K and an Air Pressure test of less than 1.0m3 @ 50Pascals. This combined performance specification is a significant advancement on its legacy portfolio. The resulting stable internal air temperatures could achieve 230C with little variance diurnally and inter-seasonally without resort to fossil fuels and mechanical ventilation or space heating.
