Managing within Sustainable Built Environments


To develop an understanding of the key requirements for a business case/ justification in support of the implementation of ‘sustainability’ measures

Learning Outcomes

Upon completion of the assignment the student will have:

  • An understanding of the multi-disciplinary nature of many of the sustainability solutions being developed and of the emerging roles of the various built environment professions and stakeholder in these potential solutions


The technical interventions required for improving the life-cycle performance of existing multifamily buildings in relation to energy consumption and sustainability are generally well understood.  The business case that accompanies these interventions however is less well developed.  Often, the most significant energy saving measures will attract additional capital cost so it is imperative in a commercial world that the benefits of such measures are well defined.  

Major multinational corporations have shown increased interest in energy saving and sustainability measures citing Corporate Social Responsibility (CSR) policies and running costs as the main drivers. This interest is further supplemented by government incentives through finance mechanisms such as capital gains tax relief and feed in tariffs.  Cost reduction in heating bills following renovation with triple glazing and high levels of insulation in housing is more immediate.


Your client (a commercially focused developer) is currently conducting a feasibility study for the redevelopment of a 1970’s multifamily housing block. (A block of council / ‘not for profit’, housing association flats) building. The redevelopment will give the building a ‘face lift’ to improve its image, but will largely keep the current layout and fenestration pattern.

The Project Architect is encouraging your client to deliver a building that meets the Passive House standard or the Passivhaus Plus standard; the Quantity Surveyor however has raised concerns in relation to this and has advised the client that the building should only meet the minimum building regulation requirements.

You have been commissioned to examine these proposals and produce a reasoned business case for the way forward that offers best overall value.


You are free to select a building of your choice, or use the example given by your tutor. You are advised to assume the building is in London and look at current UK policy and practice.

Based on the data provided below, and data your research reveals, produce a reasoned business case for what you believe to be the best way forward (note that this is not an either-or case, and a proposal somewhere in the middle may be more feasible).

You should consider the project in terms of the lifecycle of the building not just the point of handover and current global concern about climate change.

For the client and stake holders, (the tenants), running costs and maintenance will be of critical importance.

At the same time the client is commercially aware, so capital cost and ‘value’ are also critical.

Your case should include, were relevant, simple calculations to support your proposal and details of any incentives available or financial mechanisms available.

You may need to refer to benchmark energy data to support your calculations.

Non-monetary benefits and costs may also be considered within your business case.


Measure/StandardExtra/Over CostEstimated SavingsNotes
Building Regulation Compliant Only0This is the base case scenario
Enhanced Building Fabric (Insulation)+Estimated 32% reduction in heating energyMay impact on floor area
Enhanced Building Fabric (Ins+Air Tight)++Estimated 45% reduction in heating energyMay impact on floor area
High Performance Double Glazing+Estimated 25% reduction in heating energy 
Standard Triple Glazing++Estimated 32% reduction in heating energy 
External Solar Shading+++Estimated 40% reduction in cooling loadMay impact upon window cleaning. Reduction in overheating may improve comfort
PH Standard Glazing++Estimated 37% reduction in heating energy 
Solar Thermal system Free Hot water for 75% of the year?Will only be able to serve top floors and must be frost protected.
?kWp PV Array+++Estimated output ? kWh/yr.Inverters will need to be replaced approx. every 10 years.  
MVHR system+ Healthy Filtered Air
Fully Passivhaus Classic Compliant+++Estimated 80% reduction in regulated energy 
Fully Passivhaus PLUS Compliant++++Energy Positive 

Recommended Reading (all available online)

Department of Communities and Local Government (2011). The Cost of building to the Code for Sustainable Homes.

Muldavin, R. (2010). Value Beyond Cost Savings. How to underwrite Sustainable Properties.

CIBSE (2008) Technical Memorandum 46 Energy Benchmarks

CIBSE (2000) ECON 19. Energy use in Offices

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