POST-OCCUPANCY EVALUATION

Transcription

1 POST-OCCUPANCY EVALUATION Rowner Research Project Phase Two March 215

2 The Rowner research project was undertaken in Gosport between 29 and 213. The Project was funded by Innovate UK as part of the Building Performance Evaluation programme (BPE), together with support from First Wessex, NHBC Foundation, LABC, Saint-Gobain, HCA and Taylor Wimpey. The research project at Rowner investigated the design and delivery of 24 flats, split equally over two blocks. The developments were part of a multi-phased project, the Rowner Renewal project. The first block, Block B was built to comply with the Code for Sustainable Homes (CSH) level 3 energy requirements, while the second block, Block C, was built to achieve the Fabric Energy Efficiency Standard (FEES). 1 The two blocks had different tenancy agreements, with Block B being offered as shared ownership and Block C as general needs tenancy. This project provided the Hub with the opportunity to investigate the implementation of the FEES in constructed flats for the first time. THE RESEARCH PROJECT HAD THREE PHASES: Design and construction stage Post-occupancy evaluation An overheating study This factsheet reports findings from the second phase of the research project. An electronic copy of this factsheet, along with factsheets for the other phases can be found online at: ROWNER DEVELOPMENT PROJECT The Rowner Renewal is a 145 million regeneration project near Portsmouth, Hampshire. The Rowner Research project has been facilitated by the coming together of five key partners; First Wessex, the Housing Association are the clients for the construction of the development and the ongoing support of the affordable housing. Home and Communities Agency have provided funding support to the project and worked with the Zero Carbon Hub to develop the energy standards for the dwellings that are the focus of the research project. Taylor Wimpey group are the main developers of the site and led the design, delivery and construction processes. Saint-Gobain is the organisation that supported the development of some of the innovative construction materials and systems used on this project. Local Authority Building Control provided the warranty of the homes and the Building Regulations Compliance verification process. 1. The Fabric Energy Efficiency Standard (FEES) is the proposed maximum space heating and cooling energy demand for zero carbon homes from Zero Carbon Hub 3

3 THE ROWNER RESEARCH PROJECT PHASES BUILDING BASIC INFORMATION PHASE I DESIGN AND CONSTRUCTION SEP 21 SEP 211 Phase I: The design and construction phase spanned from September 21 to September 211. During this time information regarding all aspects of the construction programme and hand over process were collected and reviewed. Five factsheets have been published for this phase, including: Concept (1/5) Design strategy (2/5) Construction process (3/5) Testing programme (4/5) Occupants perspective (5/5) First Floor Plan Flat Types 1-3 PHASE II POST-OCCUPANCY EVALUATION SEP 211 SEP 213 Phase II: The post-occupancy evaluation phase spanned from September 211 to September 213. During this time information regarding actual energy and water consumption of the properties, the indoor conditions and the occupants experience of the properties were collected and reviewed. Differences in performance between the two blocks were also noted. THREE FLAT TYPOLOGIES ON SITE 1. Two bedroom, single aspect flat Floor area 68m 2 2. One bedroom, small single aspect flat Floor area 46m 2 3. Two bedroom, multi-aspect flat Floor area 7m 2 FLAT REFERENCE KEY B-GT (1-3) Block B, Ground floor Types 1-3 B-FT (1-3) Block B, First floor Types 1-3 B-ST (1-3) Block B, Second floor Types 1-3 C-GT (1-3) Block C, Ground floor Types 1-3 C-FT (1-3) Block C, First floor Types 1-3 C-ST (1-3) Block C, Second floor Types 1-3 PHASE III P OVERHEATING STUDY SEP 212 SEP 213 Phase III: The overheating study spanned from September 212 to September 213. This phase focused on the thermal behaviour of the properties during hot weather (summer months). Indoor thermal conditions were reviewed using CIBSE standards available at the time and compared to occupant perceptions of overheating. The results of this study will feed into the Zero Carbon Hub s current national study: Tackling Overheating in Homes. SERVICES INSTALLED IN ALL FLATS Mechanical Ventilation Heat Recovery (MVHR) Efficient gas combi-boiler (programmer, room thermostat, thermostatic radiator valves (TRVs) & cylinder stat.) Low energy fitted lights For more information visit 4 Rowner Research Phase Two 215 Zero Carbon Hub 5

4 DESIGN STANDARDS AND CONSTRUCTION TESTING MONITORING PLAN The design standards for Blocks B and C were defined by a combination of Building Regulations, the developer, HCA and the Rowner Research Programme. The requirement to use a Modern Method of Construction (MMC) was met through a thin-joint masonry system. This method of construction aimed to reduce the amount of mortar used in brickwork mortar-joints, leading to reduced thermal bridging and to the better thermal performance of the external walls, as well as helping to improve structural air-tightness. Large windows were used for daylight credits under the Code for Sustainable Homes. Internal space and layout requirements were set by Lifetime Homes and HCA Housing Quality Indicators (HQI). The requirement to achieve the FEES in Block C was set by the research programme and was achieved through an additional 5mm of insulation (resulting in 15mm of blown bead EPS) in the cavity of the external walls. The other difference in the construction of the two blocks was the design details for party walls, which in the case of Block C were fully insulated and edge sealed, a detail that would correspond to a U-value of. W/m 2 K in SAP. Air-Tightness Test Three air-tightness tests were performed on one flat in each block during construction (post-weather tightness, second fix, and final finishing stage). Results from each stage, and the areas of weakness identified, were used to inform future work on site. All flats tested at completion achieved an airtighntess of <4m 3 /m 2 5Pa, as per the design intent. Co-Heating Test A co-heating test was performed within one flat in each block to measure the overall Heat Loss Coefficient (HLC) of the fabric. In both flats, a much higher HLC was measured than the HLC predicted from the design stage calculations, especially the flat in Block C (FEES). This could not be fully explained by information obtained from the results from other tests during Phase I. Results from the co-heating test in this project were questionable, most likely influenced by unusually warm temperatures and the time of year that the test was performed (April). U-Value Measurements Heat flux sensors were used within one flat in each block at the final stages of construction to measure the in-situ U-values of the walls. These measurements indicated U-values worse than the designed assumptions. This could have been due to a combination of the U-value calculation conventions, the assembly of elements during construction and the way in-situ U-values were measured. Thermographic Imaging Thermographic images of the two blocks were taken after completion to identify potential unintended thermal bridges. The design stage and as-built stage SAP calculations assumed that enhanced construction details were used for both blocks. The thermographic images identified areas of potentially additional heat loss that included areas around fitted doors and windows. This evidence implied that the y-values used in the design calculation may not have been achieved on-site. To measure actual energy and water usage of the flats under evaluation a number of monitoring sensors were installed in all flats after construction was completed, including: Electricity consumption meters Gas consumption meters Water consumption meters All sensors were set to take readings at five minute intervals. A weather station was also installed on site to record external conditions, this data was used in the analysis and interpretation of internal thermal conditions. All data was transmitted live, wirelessly, to an online portal for analysis. Monthly and quarterly internal reports produced throughout the duration of the project assisted in tracking of performance and in noting potential issues with the equipment installed. Two selected flats (Type 3, middle floor flats), one in each block, were equipped with an additional set of sensors (sub-metered flats). These included the meters listed above plus additional sub-meters used to produce a detailed breakdown of the energy consumption of the flats. This allowed the research team to monitor the efficiency of installed services and increased understanding of the occupants lifestyle. 6 Rowner Research Phase Two 7

5 ENERGY CONSUMPTION PREDICTIONS Regulated Unregulated Regulated Unregulated The primary analysis of the flats expected energy performance was conducted using the Standard Assessment Procedure (SAP25). GAS The gas supply in all flats was for space and water heating only; lights, pumps, fans, consumer and cooking appliances were electrically operated. kwh/m 2 per year Block B (CSH) Block C (FEES) kwh/m 2 per year Block B (CSH) Block C (FEES) kg/m 2 per year Block B (CSH) Block C (FEES) ELECTRICITY The primary electricity consumption was for the operation of fixed internal lighting and the mechanical ventilation system, which in all the units was System 4 of the Approved Document F: a balanced mechanical ventilation system with heat recovery (MVHR). UNREGULATED ENERGY PREDICTED GAS USE 1 The gas use in the block built to comply with the Fabric Energy Efficiency Standard was predicted to be almost 7% lower than that of the block built to Code for Sustainable Homes Level 3. PREDICTED ELECTRICITY USE The electricity use in the block built to comply with FEES was predicted to be the same as the block build to comply with Code for Sustainable Homes Level 3. This is a result of the assumption that the blocks were identical, with the same services installed and occupancy levels. PREDICTED CO 2 EMISSIONS 1 The impact of the different design standards is small with the FEES block annual carbon emissions, from regulated energy use, predicted to be 4.5% lower than the Code for Sustainable Homes Level 3 block. This was due to the relatively low carbon intensity assumed for mains gas. Unregulated energy consumption was calculated using the guidance from section 16 of SAP. This was based on the floor area of the dwellings but did not take into account the actual number of occupants and how they used the flat. Note: The graphs present the average predicted energy consumption derived 1. Includes gas used for both heating and hot water by averaging predicted energy consumption across all 12 flats per block. 1. SAP 29 fuel emission factors used 8 Rowner Research Phase Two 215 Zero Carbon Hub 9

6 AIRTIGHTNESS TEST RESULTS MEASURED GAS CONSUMPTION During the second phase of the project, and almost two years after the blocks were completed, the airtightness of a number of flats was tested to identify the level of deterioration that occurred. The test results showed that airtightness had lowered in all flats tested, with a deterioration ranging from %. A deterioration of circa 4-5% in the airtightness of both blocks was considered significant. Main observations made with regards to these results were: The removal of the boxing unit around the MVHR appeared to have a significant impact on the airtightness levels The mastic seals applied at the perimeter of the windows have remained relatively effective The soil vent pipes were not effectively sealed The penetrations in the plasterboard panels through which the MVHR ductwork entered the ceiling void could not be sealed adequately as the ductwork was flexible and it was difficult to achieve an effective seal BLOCK B kwh/m 2 per year B-GT3 B-GT2 B-GT2 B-GT3 B-FT3 Measured gas use B-FT1 B-FT2 B-FT3 B-ST3 B-ST1 B-ST2 Predicted gas use B-ST3 BLOCK C kwh/m 2 per year C-GT3 C-GT2 C-GT2 C-GT3 C-FT3 Measured gas use C-FT1 C-FT2 C-FT3 C-ST3 C-ST2 C-ST2 Predicted gas use C-ST3 There were no examples of occupants altering the flats in a way that increased air leakage No significant differences were observed between the airtightness levels achieved in units from the different blocks At completion (m 3 /m Post-occupancy (m 3 /m B-GT B-FT B-FT B-ST C-GT C-FT C-FT C-ST Deterioration (%) The measured annual gas consumption of the flats in both blocks showed great variations, even when compared between flats of the same typology located within the same block. Main contributing factors for these differences included: Different occupancy levels of the different flats Different time occupants spent at home Variations in the indoor temperatures that the occupants would perceive as comfortable Variation in the occupants understanding of the heating controls Different patterns of windows use Different amounts of hot water used Financial difficulties that may have forced some of the occupants to use less gas (noted from the interviews in certain instances) Different location and flats typologies Note from the two sub-metered flats in regards to gas consumption trends Both sub-metered flats (one occupant in each spending the majority of time at home) consumed almost 55% more gas than predicted. The occupant in Block B consumed almost 6% more gas per year than the occupant in Block C. Information relating to indoor air temperatures showed that both occupants experienced comfortable indoor environments during the heating season (i.e. the colder months), with the occupant of Block B heating the flat constantly to slightly higher temperatures than the occupant in the Block C flat. This coincided with the small differences in fabric specification between the blocks and the known influence of occupant behaviour. SAP results can never be directly comparable to real life data as the tool is designed to benchmark performance under nominal assumptions. 1 Rowner Research Phase Two 215 Zero Carbon Hub 11

7 MEASURED ELECTRICITY AND WATER CONSUMPTION Boiler Cooker MVHR Fixed lighting Appliances Block B flats (Measured) Block C flats (Measured) Predicted BLOCK B BLOCK C kwh/m 2 per year B-GT3 B-GT2 B-GT2 B-GT3 B-FT3 B-FT1 Measured electricity use B-FT2 B-FT3 B-ST3 B-ST1 B-ST2 B-ST3 Predicted electricity use kwh/m 2 per year C-GT3 C-GT2 C-GT2 C-GT3 C-FT3 Measured electricity use C-FT1 C-FT2 C-FT3 C-ST3 C-ST2 C-ST2 C-ST3 Predicted electricity use kwh per year Predicted B-FT3 C-FT3 Litres per year GT3 GT2 GT2 GT3 FT3 FT1 FT2 FT3 ST3 ST1 ST2 ST3 ELECTRICITY CONSUMPTION ALL FLATS GENERAL TRENDS The measured yearly electricity consumption of the flats in both blocks revealed large variations. The measured data included both regulated and unregulated energy use (plug loads) and were compared against as-built SAP25 predictions. The average electricity use was generally lower for all the flats than the predicted demand. The predicted consumption data was based on occupancy levels determined by the floor area. This value in reality was generally lower than what would be considered as the designed occupancy. Electricity consumption patterns would have been heavily influenced by occupant lifestyles and behavioural choices. INTER-SEASONAL VARIATIONS Minimal inter-seasonal variations in the electricity use were observed in the two blocks, with an increase in the electricity consumption during the winter months. It was observed (from the analysis of electricity use in the two sub-metered flats) that the main use of electricity in the flats was due to appliances which were a factor of people s lifestyles and more difficult to analyse (appliances may have also included portable electric radiators observed in some flats). ELECTRICITY CONSUMPTION IN THE SUB-METERED FLATS A high level breakdown of the electricity consumption of the two sub-metered flats indicated that: Most of the electricity was used for appliances Both flats showed very little energy use for lighting The measured electricity demand of the installed building services was close to SAP predictions The hours of occupancy were different to the assumptions of the standardised prediction tool Both flats used significantly less electricity than predicted WATER CONSUMPTION ALL FLATS All the flats in the development were designed to comply with level 3 of the CSH, predicting the daily use of potable water to be 15 litres per person. This was more stringent than the requirements of Part G of the Building Regulations (125 litres per person) and was achieved by specifying water efficient fittings in the bathrooms and kitchens. None of the flats were provided with white goods. The measured water consumption in most flats was much lower than the designed water use, a finding which would agree with previous observations relating to low occupancy levels. A comparison of water and gas use did not indicate any correlation between higher water use and increased demand for hot water. 12 Rowner Research Phase Two 215 Zero Carbon Hub 13

8 INSTALLED SERVICES OCCUPANT COMFORT AND AIR QUALITY PROXIES MVHR The homes were built to comply with Approved Document F 26 and all MVHR systems were commissioned during Phase I to support the research project. The results of the commissioning showed that all units operated as per design intent. The ventilation rates were spot-checked, after commissioning was complete by the research team. These checks found ventilation rates lower than the designed values and the issue was raised with the project partners. During Phase II a flow rate check was performed on the MVHR in three flats (July 213). The check identified problems in all tested units, varying from low flow rates to unbalanced systems. This highlighted the importance of early diagnosis and notification tools for such systems. It may also be indicative of similar problems in the other flats. The problems identified with the MVHR units and the low air-tightness levels measured pointed to the fact that the contribution of the MVHR to reducing gas consumption of the flats may have been less than expected. Y BOILER The space heating and domestic hot water demand was calculated through SAP based on standardised assumptions made for duration of use, demand temperatures and occupancy. The boiler efficiency data was taken from the SEDBUK 25 database and was based on tests carried out to the relevant British and ISO Standards. The efficiency of the boilers installed in the flats at Rowner in SAP25 was taken to be 91.1%. More recently SEDBUK 29 figures for this model quote an efficiency of 89%. The boilers under review, within the sub-metered flats, showed a similar efficiency of around 8%. The conversion factor (from m 3 to kwh) used was based on the Carbon Trust s 1 figure of kwh /m 3. The gas factor of the provided gas in reality would have varied based on the grid s mix, which could have an impact on the calculated efficiency. Data drop outs from the transmitters could also have impacted the calculations Internal temperature, humidity and CO 2 levels were monitored in the two sub-metered flats. These flats were able to cross-ventilate as they had multiple aspects (Type 3). Both flats were able to maintain comfortable indoor air temperatures (19-23ºC) during the winter months. CO 2 concentration (ppm) Relative Humidity (RH %) /11/11 1/11/11 1/1/12 1/1/12 1/3/12 1/3/12 1/5/12 1/5/12 1/7/12 1/7/12 1/9/12 1/9/12 1/11/12 1/11/12 1/1/13 1/1/13 1/3/13 1/3/13 1/5/13 1/5/13 1/7/13 1/7/13 1/9/13 1/9/13 C-FT3 B-FT3 C-FT3 B-FT3 CIBSE GUIDE B2 STATES THAT: Within the UK, a CO 2 level of 8 to 1ppm is often used as an indicator that the ventilation rate in a building is adequate. 1 Measured CO 2 concentration levels were below the 1ppm limit for most of the project s duration.. This could have been due to the unintended reduction in airtightness of the fabric and the occupants using windows to manage conditions. It could also have been due to the relatively low occupancy of the monitored sub-metered flats. CIBSE GUIDE A STATES THAT: The influence of humidity on warmth in moderate thermal environments may be ignored and humidity in the range 4 7% (RH) is generally acceptable. 1 The humidity levels in both sub-metered flats were within the acceptable range for most of the project s duration Rowner Research Phase Two 215 Zero Carbon Hub 15

9 OCCUPANT EXPERIENCE SCORING OF DIFFERENT ASPECTS OF THE FLATS In addition to data recorded from the sensors, a Building Use Studies (BUS) survey of occupants in the two blocks was performed in both Phase I and II. The Phase I BUS survey was carried out in March 212, which allowed the occupants to evaluate their experience of the properties during winter conditions and the Phase II survey was conducted in March 213, with occupants having experienced all seasons in the flats. Variable Phase I Phase II Comfort: Overall Design Health (Perceived) Needs Location Space Layout Storage Appearance Lighting Overall Natural Electric Controls Cooling Heating Lighting Noise Ventilation Winter Temperature: Overall Hot (1) : Cold (7) Stable (1) : Varies (7) Air : Overall Dry (1) : Humid (7) Fresh (1) : Stuffy (7) Odourless (1) : Smelly (7) Still (1) : Draughty (7) Summer Temperature: Overall Hot (1) : Cold (7) Stable (1) : Varies (7) Air : Overall Dry (1) : Humid (7) - 4 Fresh (1) : Stuffy (7) Odourless (1) : Smelly (7) Still (1) : Draughty (7) The scoring of different features of the flats is shown in the graph and plotted on a scale of 1 to 7, with 7 generally representing the highest (most favourable) outcome for the specific question. However, there are some cases where the middle of the scale would represent the most optimum response and the wording may be considered unclear. An instance of this is the question how would you describe the quality of lighting natural light rating the response from too little (score of 1) to too much (score of 7). In this case the score representing an optimum level of natural light would be 3 or 4 and not 7. PHASE I BUS SURVEY 1 out of 19 surveys were completed and returned, representing a response rate of 53%. However, 9 of the surveys returned were from Block C (FEES) and only one from Block B (CSH), making a meaningful comparison between the two blocks impossible. The homes were generally felt to be comfortable during the winter of 211. It should be noted that some residents were elderly and so potentially more sensitive to winter weather. The survey results indicated that the residents felt they had reasonably good control over the heating system. Residents reported largely positive experiences of their new homes and feedback scores compared favourably with benchmark data sets. PHASE II BUS SURVEY While all 24 flats were occupied at the time of the survey, only 13 survey forms were completed and returned for analysis, of which 1 were from Block C (FEES). The second BUS survey was carried out in March 213, by which time most residents had occupied their flats for a year or more. The overall scores for the various parameters were generally slightly lower than the first survey, possibly influenced by the novelty of a new home reducing. Flats were considered comfortable after a cold winter, however, there were signs of dissatisfaction with the air quality, which was regarded on occasions as stuffy and stale. The flats were generally noted to be less comfortable during hot weather. Closer analysis revealed that occupants in flats without the ability to cross-ventilate were less satisfied. The homes were generally considered comfortable. 16 Rowner Research Phase Two 215 Zero Carbon Hub 17

10 FINDINGS ENERGY & WATER CONSUMPTION BUILDING FABRIC OCCUPANT FEEDBACK A breakdown of gas consumption in each flat showed that some occupants were high gas consumers while others seemed to use very little, irrespective of the flat specifications. Different occupant behaviours appeared to have a strong impact on gas consumption. This, along with the minimal predicted difference in the thermal performance of the two blocks, made it difficult to accurately evaluate variation in consumption directly relating to the different insulation specification. The measured gas use in both blocks was higher than predicted, with a larger variation measured in Block B (CSH). Even though measured gas consumption relies heavily on specific preferences of the occupant, and time spent at home, in the case of Block B the insulation levels and the uninsulated party walls may have also played a role. The average gas consumption measured in Block C (FEES) was closer to the predicted value. Electricity demand in the flats was generally much lower than predicted (based on total regulated and unregulated electricity consumption predictions). The main difference was noted in the electricity demand for fixed internal lighting and appliances within the sub-metered flats. Unregulated (plug) energy loads were also lower than predicted in the case of the two sub-metered flats,. Block C used marginally less electricity than Block B, which was attributed to different lifestyle choices of the occupants and potentially to different levels of occupancy in some of the flats. The predicted consumption values were based on standardised occupancy. However the measured water use in nearly all flats was lower than the predicted values. The air permeability of all the flats tested during Phase II worsened from the levels measured at the time of build completion. A significant contributor to this was the removal of the boxing around the MVHR unit to ensure access to the control panel for maintenance. This could have been avoided by early planning and could be rectified by reinstalling the boxing unit with provision for maintenance access. Some of the other areas of air leakage identified were around soil pipes, which were highlighted during construction but for which remedial work would be challenging. The difference in the two block specifications appeared to have a small impact on the thermal performance of the units. This difference was more obvious during the winter period. The gas consumption of the sub-metered flat in Block C (FEES) was close to that of the sub-metered flat of Block B (CSH) indicating that results obtained from the co-heating test may have been influenced by the weather conditions when they were being carried out. Occupants felt comfortable in their new homes and reported generally good indoor thermal conditions. Measured temperatures, humidity and CO 2 levels from the two sub-metered flats supported the occupants perception and BUS scoring. Occupants seemed satisfied with levels of control over building services and it appeared that they were largely able to control the systems. Nevertheless, during the course of the project - and during semi-structured interviews - it was shown that many occupants had difficulty understanding aspects of their heating and ventilation systems. This lack of knowledge was more evident with regard to their MVHR systems, with some residents assuming that the systems had been installed for cooling purposes. Most occupants were unable to understand the energy efficiency aspect of their new homes in tangible terms, due to a lack of awareness of fuel costs. 18 Rowner Research Phase Two 215 Zero Carbon Hub 19

11 RECOMMENDATIONS ENERGY EFFICIENT HOMES Building homes to higher insulation levels reduces the heating load required during the cold period of the year, benefiting the occupant with reduced running costs. Ventilation in homes is becoming an increasingly important element of the design, especially in highly airtight homes supported by mechanical ventilation systems. When developing new homes ventilation, indoor air quality and the risk of overheating must be acknowledged and carefully considered. Setting clearly defined energy performance targets for new homes - as in the case of FEES in this example - will assist the designer/developer in developing robust and cost-effective solutions. The importance of achieving as-built performance closer to the design is now widely acknowledged. Learnings from this project have informed the larger Zero Carbon Hub Performance Gap project with many common issues identified across the industry. NEW TECHNOLOGIES Building services, in particular innovative newer systems, need to be clearly understood by the occupants and easily controllable. This relies on a simple explanation of the operating principles during the handover process to the consumer, maintenance schedules and clear interface design for controls. All installation, commissioning and maintenance requirements for building services must be adequately considered before including them in developments. Special attention and skills training should be applied for systems that are unfamiliar to the construction and installation teams. SOCIAL The impact of behaviour on fuel bills must also be explained to occupants. Where developments are not part of a monitoring programme this can be achieved by meeting with residents to discuss the impacts of how they use their homes, and helping to compare their energy bills to benchmarks for similar properties. RESEARCH COMMUNITY While undertaking monitoring projects, the volume of data collected must be considered against the usefulness of the information and time required for processing. Cleaning data sets to achieve useful information can be time consuming and the value of short time intervals should be re-evaluated to ensure a reasonable processing time is achievable. Consideration should also be given to the practicality of accessing equipment for the purpose of repairs and maintenance. There should be minimal disruption to residents and any maintenance or repair should be scheduled around residents, which may be outside working hours and on weekends. Unregulated electricity forms a large proportion of electricity use in homes and varies considerably. While it is not possible to account for occupant behaviour, the assumptions and methods currently available should be re-evaluated and revised to ensure that future energy use targets are met. Occupant surveys, in addition to standardised questionnaires, should include face to face interviews with residents to ensure that their specific queries and habits are taken into account. When using modelling tools and benchmarks it is important to understand the base assumptions and conditions so that analysis is useful and effective. Results from the co-heating test in this project were questionable, most likely influenced by unusually warm temperatures and the time of year that the test was performed. Even though this is a useful end-ofline test to validate as built fabric performance, there are currently no formally standardised methods for testing whole house heat loss. More research into this method is required in parallel with the development of in-line tests that can be applied at an industry rather than research scale. More detailed work is required to understand what impact occupancy (type and patterns) has on energy consumption. FOR THE DEVELOPMENT OF BUILDING REGULATIONS Data from the monitoring of homes built to recent standards of energy efficiency should be used to strengthen the assumptions in standardised tools like SAP. This is important to inform the development of future standards and also to help industry innovate and improve the skills and knowledge necessary to deliver low energy homes. Information on performance gap issues, ventilation and overheating risks will need to be evaluated and considered as policies develop. This will ensure that energy efficiency targets are not compromised and that the right pool of knowledge exists to inform industry s progress. 2 Rowner Research Phase Two 215 Zero Carbon Hub 21

12 OTHER DOCUMENTS IN THIS SERIES The Zero Carbon Hub was established in 28, as a non-profit organisation, to take day-to-day operational responsibility for achieving the government s target of delivering zero carbon homes in England from 216. The Hub reports directly to the 216 Taskforce. To find out more, or if you would like to contribute to the work of the Zero Carbon Hub, please contact: info@zerocarbonhub.org Zero Carbon Hub Layden House Turnmill Street London EC1M 5LG This report is available as a PDF download from:

13 Zero Carbon Hub Layden House Turnmill Street London EC1M 5LG T E.