A Simplified Analysis Method for Predicting the Impact of Thermal Insulation on Heating and Cooling Loads in Syrian Residential Buildings

This document is a translated summary of a research paper presented in the Proceedings of the 2nd Conference: People and Buildings, held at the Graduate Centre, London Metropolitan University, London, United Kingdom, on 18 September 2012. This research is based on the author's Master's thesis, which contains the full methodology, datasets, and comprehensive findings of the study. The complete thesis can be shared with interested researchers upon request.

Network for Comfort and Energy Use in Buildings (NCEUB)

Abstract

This research presents a simplified analysis method aimed at reducing energy demand in Syrian residential buildings by implementing highly cost-effective and structurally feasible passive design solutions. The primary focus is on reducing heating loads, which constitute more than 55% of total residential energy consumption, and limiting heat loss without causing indoor overheating during the summer months.

The simplified analysis method was developed using detailed thermal simulation software (IES-VE), evaluating several combinations of passive design strategies across different building materials, glazing types, and climatic zones. A direct correlation is established between the developed methods, total annual heating energy requirements, and cooling loads. Finally, an optimised envelope specification is recommended.

1. Introduction

The thermal insulation of a building's envelope significantly influences both initial capital construction costs and long-term operational energy costs. In 2007, the Ministry of Electricity and the National Energy Research Center (NERC) in Syria issued the Building Thermal Insulation Code.

The current code-recommended structural envelope standard specifies:

• A maximum U-value (thermal transmittance) of 0.8 W/m²K for external walls (typically achieved using an uninsulated double-wall system consisting of two layers of 20 cm concrete blocks with external limestone plastering).
• A maximum U-value of 3.5 W/m²K for double-glazed windows.

To date, few studies have adequately investigated the holistic impact of building insulation on thermal performance under specific Syrian climatic conditions. Furthermore, simple, comprehensive mathematical relationships linking envelope insulation levels directly to total annual heating and cooling loads have not been widely established.

Limited existing investigations have focused on reducing energy demand by applying various types of thermal insulation to the building envelope. However, these studies have often relied on overly simplistic methods to categorise and propose optimal solutions. For instance, Ajjoub (2010) recommended the Syrian Building Code standard as the optimal insulation tier among all proposed options, whilst largely overlooking the financial implications, structural wall thickness, and spatial efficiency of the double-wall system.

This research proposes a simplified analysis method to assess the precise impact of envelope thermal insulation on total annual heating and cooling loads in Syria. First, a representative model of a typical Syrian residential apartment is defined. Next, the results of the parametric analysis are summarised. Finally, the simplified analysis method and the optimised structural recommendation are presented.

2. Parametric Modelling

A typical Syrian residential apartment was modelled using the Integrated Environmental Solutions Virtual Environment (IES-VE) software. The internal heat gains and occupancy profiles were configured to represent typical Middle Eastern residential lifestyles:

• Lighting Density: 7.8 W/m²
• Equipment Density: 8.0 W/m²
• Average Occupancy Density: 25.5 m²/person
• Cooling Setpoint: 25°C
• Heating Setpoints: 19°C for the living room; 18°C for bedrooms, kitchen, and bathrooms
• Window-to-Wall Ratio (WWR): Maintained as a constant parameter throughout the simulations

Several envelope variables were parametrically adjusted to evaluate annual heating and cooling loads across different wall assemblies and glazing types, as detailed in Tables 1 and 2 below.

Table 1: Wall Assemblies, Thicknesses, and U-values

Table 2: Glazing Specifications Used in Simulations

The experimental simulation runs were divided into three main phases:

• Phase 1: Applying different wall assemblies (Table 1) to the apartment model to isolate and determine their individual impacts on annual heating and cooling demands.
• Phases 2 and 3: Upgrading the glazing system from single to double, and then to triple glazing (Table 2), and running the full matrix of wall simulations under each glazing scenario.

3. Discussion of Results

3.1 Impact of Wall Assembly and Insulation

To determine the direct impact of wall insulation on heating and cooling loads, a baseline simulation was run for an apartment located in Damascus, Syria.

Figure 1 shows the simulated annual heating and cooling energy requirements when windows are kept at single glazing (U = 5.6 W/m²K). The data demonstrates a strong non-linear relationship: as the thermal insulation of the building envelope increases (lower U-value), both heating and cooling loads decrease, with the rate of reduction diminishing at exceptionally low U-values.

Chart

Annual heating and cooling loads by wall assembly (single glazing baseline)

As envelope insulation improves (lower U-value), both heating and cooling loads decrease — with diminishing returns at very low U-values. Damascus, Syria.

3.2 Impact of Wall Thickness and Cost

Figure 2 correlates wall construction costs per square metre (£/m²) against total wall thickness and thermal performance.

As expected, improving the thermal properties of uninsulated masonry walls dramatically increases both wall thickness and material costs. However, introducing dedicated insulation material (for example, polyurethane board) into the wall assembly breaks this trend. By integrating a thin layer of insulation, a 50% reduction in total wall thickness and a 50% improvement in thermal performance were achieved simultaneously compared to the uninsulated double-wall system recommended by the Syrian Code, at virtually the same capital construction cost.

Chart

Annual heating and cooling loads by wall assembly (single glazing baseline)

As envelope insulation improves (lower U-value), both heating and cooling loads decrease — with diminishing returns at very low U-values. Damascus, Syria.

3.3 Impact of Glazing Upgrades

Figure 3 presents the combined impact of glazing specifications and wall insulation on the building's total annual heating loads.

Upgrading from single to double glazing yielded a massive reduction in heating demand. In the baseline wall scenario, double glazing achieved a 36.92% reduction in heating loads, which escalated to an overall heating load reduction of 66.30% when combined with improved wall insulation. Conversely, upgrading from double to triple glazing yielded negligible thermodynamic benefits, resulting in an additional heating load reduction of less than 1%, which does not justify the high capital cost of triple-glazed units in Syria's climate.

Chart

Annual heating and cooling loads by wall assembly (single glazing baseline)

As envelope insulation improves (lower U-value), both heating and cooling loads decrease — with diminishing returns at very low U-values. Damascus, Syria.

3.4 Formulation of the Simplified Analysis Method

Based on the simulation matrix, a robust mathematical correlation was found between envelope U-values, glazing types, and annual heating loads. The correlation between envelope insulation and cooling loads was weaker, as summer heat gain in Syrian residential units is heavily dominated by solar radiation through windows and ventilation rates rather than conduction through opaque walls.

4. Conclusion and Strategic Recommendations

This research proves that whilst opaque and transparent insulation strategies are highly effective at reducing winter heating loads in Syria, they have a limited impact on summer cooling loads, which must be addressed through shading and natural ventilation.

A simplified analysis method has been successfully formulated, allowing designers to predict annual heating and cooling loads as a function of wall U-values and glazing types.

The primary recommendation of this study is the adoption of an optimised, highly cost-effective, and space-efficient envelope specification:

External Walls: An insulated single-skin wall consisting of a 10 cm concrete block, a 5 cm polyurethane insulation board, and external limestone plastering (total thickness of 25 cm).

Target Wall U-value = 0.4 W/m²K

Windows: High-performance double-glazed units.

Target Glazing U-value = 1.9 W/m²K

This recommended specification is projected to achieve a 61.24% saving in annual heating loads compared to the baseline, outperforming the Syrian Thermal Code's double-wall standard (which achieves a 49.98% saving) at the same capital cost, whilst delivering a lighter, thinner, and structurally superior wall assembly.

References

Ajjoub, F. (2010). Designing a low energy dwelling in Syria using Passive Design strategies to achieve thermal comfort. Oxford: Oxford Brookes University.

Keshkeh, H. (2007). Building Thermal Insulation Code in Syria. Damascus: The Ministry of Energy and Electricity / National Energy Research Center (NERC).