Planning policy - section 3F: research

4. Proposal Overview

4.1 Introduction

In responding to the aim of the Scottish Government to develop a Scotland wide Section 3F development plan policy, we have considered both the established literature in relation to the most efficient, cost-effective and future-proof means of reducing CO₂ emissions from buildings, and the issues raised by planning professionals administrating current Section 3F planning policies in Scotland. This research resulted in the development of two distinct responses that might be appropriate for the Scottish Government to consider at this juncture.

In respect to calculating an appropriate level for LZCGT contribution, both proposals utilise predicted energy consumption data, modelled for domestic buildings ranging in size from 25m² to 300m² using formulae prescribed by SAP 2012 (BRE, 2014). In this respect three scenarios were developed to better represent the impact of expected improvements in fabric energy efficiency (Appendix B).

4.2 Proposal 1: A Minimum LZCGT Contribution Standard

The first proposal simply satisfies the research objectives as stated in the brief relative to Section 3F Policy as currently enacted. Section 3F policy does not seek to reduce the CO₂ emissions from new buildings beyond what is already legislated for at Building Standards; it simply defines the proportion of that reduction that should be achieved through the use of LZCGT.

The proposal defines a realistic minimum LZCGT contribution to CO₂ emission reduction in new buildings that could be sought by Section 3F policy and the method by which this contribution could be calculated to establish policy compliance. This is achieved through a simple and pragmatic approach which models the potential impact of utilizing LZCGT to replace a proportion of heat or electrical demand in domestic buildings on overall energy consumption; and interpreting the resultant graphical data in relation to what might be a reasonable minimum expectation of LZCGT use under different CO₂ emission reduction standards. The resultant LZCGT contribution level and compliance methodology can be applied to both domestic and non-domestic buildings.

In pursuing this methodology it is recognised that setting a minimum level of LZCGT contribution that is too high might have adverse consequences on long-term goals for CO₂ emission reduction, energy security and the ability to achieve wider societal goals. In particular it was concluded that the contribution level should not preclude architects from taking a fabric first approach or developing innovative passive design solutions, and should not restrict the ability to deliver affordable housing in a cost-effective way. It is also acknowledged that what is 'reasonable' is open to interpretation. As a consequence the level of LZCGT contribution calculated by this method was subsequently evaluated with respect to both implied and explicit expectations set out in current Scottish Government legislation i.e. Section 7 of the Scottish Technical Standards (Domestic Buildings), the Climate Change (Emissions Reduction Targets) (Scotland) Act 2019, and the Climate Change Plan.

4.3 Proposal 2: A Whole Building Approach

The second proposal takes a whole building approach which diverges significantly from the existing Section 3F policy and would therefore require new legislation. It re-invents this policy in a way that plays to the strengths and skillsets of planning whilst complementing and supporting the existing whole building approach to CO₂ emission reduction taken by building standards. It is anticipated that this proposed approach will add leverage to the type of sustainable and passive design solutions many planning authorities currently advocate, and address fundamental societal issues of consumption and the equitable use of resources; whilst simultaneously reducing energy demand, increasing fabric energy efficiency and incentivising the use of LZCGT.

This proposal is solely focussed on the domestic sector, and in essence seeks to cap annual energy demand in new dwellings to an 'acceptable' per capita level. This level will be calculated with reference to the predicted per capita energy consumption of modestly-sized energy efficient dwellings (45m² to 100m²). As a consequence this policy will have a greater impact on dwellings with larger per capita heated living spaces.

Architects and developers will have the option of meeting the acceptable annual energy demand (AAED) calculated for their proposed building through any combination of design, fabric energy efficiency, equipment efficiency or LZCGT. Applicants will be encouraged to meet this target as far as possible through good design and fabric energy efficiency measures alone to avoid potential carbon lock-in. However if this is not feasible any remaining demand above the acceptable level will have to be met through the use of zero-carbon renewable energy resources. Policy compliance will be established by completing a simple standardised spreadsheet with data taken directly from the building's SAP document.