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Buildings Energy & Water Efficiency Assessments

Background:

Following concerns raised by the local planning authority regarding the energy efficiency of the proposed house design, ESS Consultants was commissioned by the developer to conduct a comparative analysis against the criteria set out in Part L1A of the current UK building regulations.  A further comparison was to be made with the Passive House standards.

 

The Analysis:

The analysis was performed at three levels for energy, water and embodied energy in construction materials using location specific climatic data and utility costs.

 

Efficiency Improvements:

The local building code requirements for energy and water efficiency was set as the baseline model. For the proposed design, 24 energy and 8 water efficiency measures were investigated. Selection of the best was based on the highest % reduction per £1 of capex spend applied.

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U-Values             House to Building   Passive House  Proposed

                              Code Standard         Standard         House

Roof                             0.13                     0.15                0.11

Walls                            0.15                     0.15                0.10

Floor                            0.13                     0.15                0.19

Windows                     1.40                     0.80                0.90          

Windows SHGC          0.50                    0.60                 0.50

The Results:

The performance results are summarised below from which it can be seen that the proposed design despite its high level of glazing delivers a 50% reduction compared with building code design.

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Compared with local building code design, the proposed development delivers:

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  • a 50% reduction in primary energy use

  • a 54% reduction in CO2 emissions

  • a 29% reduction in water use

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In additional to excellent structural U-values, the proposed house benefits from a number of additional efficiency features such as:

 

  • High performance ground source heat pump which is about 3.5 x more efficient than a condensing gas boiler

  • MVHR to provide controlled fresh air supply thus reducing space heating requirements in winter

  • Fresh air supply heated (winter) and cooled (summer) via underground supply ductwork

  • Solar PV generation to provide 20% carbon free electricity with battery storage

  • All water faucets designed to flow rate of 6l/min and showers to 10l/min

  • Rainwater harvested from 100% of the roof to reduce water usage for irrigation and outdoor uses

 

For more information or to discuss your project contact us.

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