Building Performance Analysis
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Energy modelling is required for domestic and non-domestic buildings to demonstrate compliance with Part L for Building Control and CO2 emissions targets for planning. It is an essential part of the design and construction process and aims to ensure buildings are designed with energy efficiency and cost of operation in mind.
Energy Assessments are the accompanying reports for planning applications for domestic and non-domestic buildings that demonstrate the proposed CO2 emissions reductions over Part L and the financial contribution for ‘zero carbon’ homes. The reports demonstrate compliance with national and local policies and regulations, thus establishing a scheme’s suitability for planning approval and ensuring the approved scheme can achieve its planning conditions at practical completion.
An LZC study assesses the feasibility of installing low and zero carbon energy technologies and quantifies the anticipated energy savings and CO2 emissions reductions. This report can be used to gain BREEAM credits and demonstrate compliance with planning requirements.
Air tightness requirements in buildings are becoming increasingly demanding. Consequently, it is crucial that design principles and techniques are embedded in the design and construction of buildings to ensure that air tightness levels are achieved at practical completion. We provide consultancy services that systematically work through architectural detailing and construction methods to reduce the likelihood of air leakage. During construction inspections a smoke survey can be undertaken to assess the quality of workmanship and highlight leakage paths. Interim air pressure testing with fans can also be undertaken to determine the air permeability result at a given stage in the construction process and inform the anticipated test result at practical completion.
Thermal bridging analysis is often crucial in achieving Part L targets and is used to reduce the risk of condensation within the building fabric. Thermal bridging results where one or more building elements, that are more thermally conductive than the rest of the building envelope, meet each other. These bridges can be designed-out to reduce surface condensation risk through an iterative process of detailed psi-value calculations and careful architectural detailing.
Fenestration products have complex component geometries and material properties, which require the use of finite element analysis (FEA) in order to quantify the heat losses in thermal bridges such as frames, transoms and mullions. Calculating the heat losses of these products and systems determines the U-values than can be used for Part L energy modelling and the potential risk of surface condensation.
Dynamic simulation modelling is used to ascertain the risk of overheating and maximise occupant comfort within a building, it is also necessary to demonstrate compliance with the London Plan. The analysis aims to ‘design out’ and reduce need for active cooling as much as practically possible. Guidance on U-values, thermal mass, airtightness, shading and the optimal ventilation and mechanical services strategy can be provided by our team based on the modelling outputs.
Natural ventilation uses outside air movement and pressure differences to both passively cool and ventilate a building without the use of fans, which reduces installed plant costs and energy consumption. A successful natural ventilation strategy must also deliver high thermal comfort and adequate fresh air for the ventilated spaces, which requires dynamic thermal modelling to ascertain the level of effectiveness and the exact speed and volume of air flow.
Detailed calculations that determine gains, losses and other environmental conditions are required to establish the heating and cooling load requirements for buildings. These are the fundamental basis for sizing HVAC plant and provide a basis for optimising the building fabric and fenestration design.
Condensation in building components occurs when warm moisture-laden air meets cold vapour-resistant surfaces. Condensation has two primary forms: surface condensation (visible on surface) and interstitial condensation (hidden between construction layers). A good building envelope design will have systematically designed-out the risk of condensation by performing a Condensation Risk Analysis which would highlight the potential risk and verify that the proposed design solution has mitigated that risk.
Dynamic Condensation Risk Analysis using WUFI software provides a highly detailed and accurate evaluation of the risk of interstitial condensation, mould growth, frost risk and corrosion. This hygrothermal (the interactions between heat and moisture) analysis provides the basis for recommendations on material types and thicknesses, cavity dimensions and appropriate ventilation levels to achieve best practice design standards such as EN 15026.
(Note that this analysis is now a requirement for all internally insulated external walls.)
Moisture must be controlled within buildings to prevent increased risks of condensation, damage to materials, reduced thermal conductivity of insulation and associated air quality issues. Existing buildings, often constructed with moisture-permeable materials, must have appropriate strategies to avoid these risks. A structural moisture survey measures the current levels of moisture in a structure and aims to ascertain its cause. Subsequently, appropriate ventilation rates can be recommended to minimise the risks of structural moisture. This is a mandatory requirement for BREEAM Domestic Refurbishment and should be considered best practice for extensive refurbishment projects.
Computational Fluid Dynamics (CFD) modelling is used in various situations within buildings to assess the effectiveness of ventilation strategies in achieving the desired air quality and indoor temperatures, either by natural means or forced convection. CFD is critical in assessing the effectiveness of a given system in achieving the desired air flow through zones. The modelling results inform the recommendations and guidance on thermal mass, equipment location and the optimal ventilation and mechanical services specification.
Energy Performance Certificates (EPCs) estimate the amount of energy a building will consume and are the ultimate output from Part L energy modelling. They are a legal requirement for domestic and non-domestic buildings under the Energy Performance of Buildings Directive. As of 2018 landlords cannot grant new tenancies for properties with an ‘F’ or ‘G’ rating. EPCs are typically produced at project practical completion and can also be produced for existing buildings. Low EPC ratings could in part be due to poor modelling, consequently Eight Associates always ensures that all calculations are done in full detail without generic data to ensure the most accurate results.
Display Energy Certificates (DECs) reflect the actual amount of energy a building has consumed over the past 12 months, based on an A to G scale. They are a legal requirement for all public buildings over 250 sq metres under the Energy Performance of Buildings Directive. They can be a useful tool to compare how a building is performing in comparison to its predicted energy consumption, which is provided by the EPC.
An internal daylight analysis calculates the daylight levels and distribution of the daylight inside a room, which is key tool in the design of a building’s fenestration and form. As well as ensuring the building will receive the necessary levels of daylight and maximise occupant comfort, the analysis can be used to comply with the BREEAM or LEED daylighting credits.
Daylight and Sunlight Impact assessments calculate the impact on the daylight levels experienced by existing neighbouring amenities (dwellings, non-domestic uses, gardens, open spaces) as a result of a proposed development. The daylight impact is measured in terms of VSC, ASPH, No-sky line and daylight hours. This analysis forms an essential component of any planning application that would increase overshadowing or decrease access to natural light on an existing amenity.
A right of light (ROL) may be acquired by ‘anyone who has had uninterrupted use of something over someone else’s land for 20 years without consent, openly and without threat, and without interruption for more than a year,’ according to RICS. Where development will have any impact on the light received by neighbouring properties it is essential that Right of Light is considered. The Right of Light assessment will calculate the book value compensation and will highlight what options there are for dealing with the resulting ROL issues.
Glare occurs when direct light is received on an object like a screen and there is high contrast between the screen and the surrounding areas. A glare analysis highlights the areas where the glare risk is high, evaluates the daylight glare probability (DGP) for different workstations in the space, and provides recommendations and measures to reduce the glare.
ASHRAE energy modelling uses the ASHRAE methodology (mainly used in North America, but also Asia, Australasia and the Middle East) to determine the likely energy consumption of a building and demonstrate compliance with the ASHRAE standard and achieve LEED energy modelling credits.
Karsten tube testing is conducted for existing building elements to calculate the water absorption (A-value) of materials e.g. brickwork which provides the essential data for WUFI condensation calculations to determine the interstitial condensation risk.