Development and validation of detailed building, plant and controller modelling to demonstrate interactive behaviour of system components

As plant modelling becomes capable of more complexity and detailed resolution, new opportunities arise for the virtual evaluation of discrete plant components such as flow control and energy conversion devices, and controllers. Such objects are conventionally developed and tested at the prototype stage in a laboratory environment. Designers now seek to use modelling technology to extend their understanding from limited laboratory test results to full building and plant system analysis. This paper describes the development of a modelling system, using ESP-r, for typical United Kingdom domestic house types with hydronic gas or oil fired central heating including radiator and underfloor heating systems, and with a variety of conventional or advanced control types. It demonstrates the ability of detailed building and plant modelling to reveal unexpected insights into how real control systems perform in combination with other plant items and in different building types, including estimation of their influence on annual energy consumption. Comparisons with measurements taken in test rooms confirm that the observed behaviour of controls is realised in practice. The authors conclude that the complex dynamic interactions that take place between the various elements that make up a real building energy system have an important influence on its overall energy performance, revealing causes of variance that cannot be identified by laboratory testing alone, or by simplistic energy assessment tools

Analysis of retrofit air source heat pump performance : results from detailed simulations and comparison to field trial data

In the UK, gas boilers are the predominant energy source for heating in housing, due primarily to the ready availability of natural gas. The take-up of heat pumps has lagged far behind Europe and North America. However, with the development of standards for low and zero-carbon housing, gas price rises and the depletion of the UK's natural gas reserves, interest in heat pump technology is growing. Heat pumps, particularly air source heat pumps (ASHP), have the potential to be a direct, low-carbon replacement for gas boiler systems in housing. In this paper, monitored data and simulations were used to assess the performance of ASHP when retro-fitted into a dwelling. This required the development and calibration of a model of an ASHP device and its integration into a whole-building, dynamic simulation environment. The predictions of the whole-building model were compared to field trial data, indicating that it provided a suitable test bed for energy performance assessment. Annual simulations indicated that the ASHP produced 12% less carbon that an equivalent condensing gas boiler system, but was around 10% more expensive to run. However, the proposed UK renewable heat incentive transforms this situation, with income from ASHP heat generation exceeding the fuel costs

The York Energy Demonstration Project: Final Report

In the early to mid 1990s the UK government funded a series of demonstration projects in local authority housing designed to implement a wide range of energy saving measures which could be incorporated into modernisation programmes. This programme (the Greenhouse Programme) ran from 1991 to 1994 and funded some 183 schemes (over 50,000 dwellings) of which the York project was one. In common with many energy demonstration projects, the York Project had two main aims. The first was to confirm that the application of readily available technology could deliver significant energy benefits within the context of a routine local authority housing modernisation programme. The second was to extract lessons for the operation of future energy conscious modernisation schemes

고단열丶고기밀 공동주택 온열쾌적 유지 및 난방에너지 저감을 위한 저온난방시스템 타당성에 관한 연구

학위논문(석사) -- 서울대학교대학원 : 공과대학 건축학과, 2022. 8. 여명석.According to relevant statistics, residential buildings such as apartments in buildings account for 43.4% of the energy consumption of the entire building sector. In addition to the energy consumption of the electrical system, the next most important energy consumption system is the heating system. By examining and analyzing the literature of related studies, this thesis discovered that, while the thermal insulation and tightness of apartment building envelopes have greatly improved in recent years, the heating load has been reduced to a relatively low level. Regardless of whether individual or district heating is used, hot water at a higher temperature is still used to transfer heat for the room through radiant floor heating panels to meet the indoor heating load. The strengthening of the thermal insulation of the envelope has led to a continuous decrease in the heating load of apartments, which provides theoretical possibilities for the application of low-temperature heating systems in residential buildings. Therefore, in this thesis, two low-temperature heating systems using individual gas boilers as heat sources and three low-temperature district heating systems were constructed by referring to the forms of related existing heating systems. To analyze the applicability of low-temperature heating systems in high - insulation high-tightness apartment buildings, a model of the relevant building and heating system was created using the dynamic simulation software EnergyPlus 9.5 as a research tool. For assessing the applicability of the low-temperature heating system, an assessment strategy was constructed from three perspectives: heating performance, thermal comfort, and energy consumption. Finally, according to the evaluation system, by comparing with the existing heating systems. The main results of this study are as follows. (1) It was confirmed that all low-temperature heating systems can meet the indoor heating demand. Floor surface temperatures and room temperatures tend to be lower than those of existing heating systems. And the floor surface temperature does not exceed the upper limit 29℃ required in the ASHARE HANBDBOOK. (2) Both low-temperature individual heating systems can improve the heating performance, low temperature individual heating system that use outdoor reset control to regulate water temperature can further improve heating performance. In the assessment about low-temperature district heating systems, it was found that the low-temperature district heating systems with HIU equipment has the most significant improvement in heating performance. (3) As the supply water temperature decrease, the low-temperature heating systems often require longer operating times to meet the indoor heating load. That is why individual low-temperature heating systems with outdoor reset control and district low heating systems with HIU have the longest operating times. In contrast to the runtime scenario, however, energy savings in the study period of the two longest-running low-temperature heating systems that use different heat sources are the most significant.관련 통계에 따르면 건물 내 아파트 등 주거용 건축물이 전체 건축부문 에너지 소비량의 43.4%를 차지하고 있다. 전기 시스템의 에너지 소비 외에 다음으로 주목할 만한 것은 난방 시스템의 에너지 소비이다. 본 논문은 관련 연구문헌을 살펴보고 분석함으로써 최근 아파트 건물 외피의 단열성능과 기밀성은 개선되는데 난방 부하가 상대적으로 낮은 수준으로 감소하였음을 발견했다. 하지만 개별 난방이든 지역 난방이든 상관없이 기준 난방시스템에서 높은 온도의 온수를 이용하고 복사 바닥 난방 패널을 통해 실내의 열을 전달하는 데가 유지하고 20세대 초반과 큰 변화는 없다. 외피 단열성능의 강화로 아파트의 난방 부하가 지속적으로 감소하면서 주거용 건물에 저온 난방 시스템을 적용할 수 있는 이론적 가능성을 제공하고 있다. 이에 본 논문에서는 개별 가스보일러를 열원으로 사용하는 저온 난방시스템과 기존 지역난방시스템을 참고하여 저온 지역 난방시스템을 구축하였다. 단열성과 기말성이 좋은 아파트 내 저온난방시스템의 적용가능성을 분석하기 위해 동적 시뮬레이션 소프트웨어 EnergyPlus 9.5를 연구 도구로 사용하여 해당 건물 및 난방시스템의 모델을 만들었다. 그리고 저온 난방 시스템의 적용 가능성을 평가하기 위해 난방 성능, 열적 쾌적성, 에너지 소비의 세 가지 관점에서 평가방범을 구축하였다. 마지막으로 평가 시스템에 따라 기존 난방 시스템과 비교하였다. 본 연구의 주요 결과는 다음과 같다: (1) 모든 저온 난방 시스템이 실내 난방 수요를 만족시킬 수 있음을 확인하였다. 바닥 표면 온도와 실내온도은 기존 난방 시스템보다 낮은 경향이 있다. 그리고 바닥면 온도는 ASHARE HANBDBOOK에서 요구하는 상한 29℃를 초과하지 않다. (2) 저온 개별 난방 시스템의 경우에서 난방 성능을 향상시킬 수 있으며, 실외 리셋 컨트롤을 사용하여 수온을 조절하는 저온 개별 난방 시스템은 난방 성능을 더욱 향상시킬 수 있다. 저온지역난방시스템에 대한 평가에서 HIU 장비를 갖춘 저온지역난방시스템이 난방성능을 가장 크게 향상시킨 것으로 나타났다. (3) 공급 온수온도가 낮아짐에 따라 저온 난방 시스템은 실내 난방요구를 만족하기 위해 더 긴 작동 시간을 필요로 하는 경우가 많다. 그렇기 때문에 실외 리셋 제어 기능이 있는 개별 저온 난방 시스템 및 HIU 기능이 있는 지역 저난방 시스템의 작동 시간이 가장 길다. 그러나 런타임 시나리오와 달리, 서로 다른 열원을 사용하는 가장 오래 지속되는 두 저온 난방 시스템의 연구 기간 중 에너지 많이 절약이 된다.Chapter 1. Introduction 1 1.1. Study Background and Purpose 1 1.2. Research Approach and Scope 4 Chapter 2. Preliminary Study 8 2.1. Changes in the heating load of Apartment in Korea 8 2.1.1 Development of thermal insulation of the building envelope 8 2.1.2 Changes in the heating load of Apartment 9 2.2. Existing space heating systems in Korea 12 2.2.1 Radiant Floor Heating System 14 2.2.2 Independent Heating with Individual Boilers 23 2.2.3 District Heating 30 2.3. Low-temperature Hydronic Heating Systems 36 2.3.1 Definition of low-temperature heating system 37 2.3.2 Low-temperature District Heating 40 2.3.3 Heat Interface Unit 42 2.4 Summary 45 Chapter 3. Research Subjects 47 3.1. Research Apartment Object 47 3.1.1 Apartment model for simulation analysis 47 3.1.2 Heating load analysis of object multi-family building. 51 3.2 Space heating system 55 3.2.1 Gas Boiler 55 3.2.2 Floor Radiant Heating Panel 56 3.2.3 Control for heating system 57 3.3 Assessment strategy 59 3.3.1 Heating Performance and Thermal Comfort 59 3.3.2 Energy Consumption 60 3.4 Summary 61 Chapter 4. Evaluation of the suitability of low temperature heating systems 63 4.1 Assessment Overview 64 4.2 Assessment of the suitability of individual low-temperature heating systems 70 4.2.1 Applicability evaluation of individual low-temperature heating systems with fixed supply water temperature 70 4.2.2 Applicability evaluation of individual low-temperature heating systems with outdoor reset control 78 4.3 Assessment of the suitability of district low-temperature heating systems 85 4.3.1 Applicability evaluation of district low-temperature heating systems with constant supply water temperature 86 4.3.2 Applicability evaluation of low-temperature district heating systems with outdoor reset control 91 4.3.3 Applicability evaluation of district low-temperature heating systems with heat interface unit 97 4.4 Summary 102 Chapter 5. Conclusion 105석

Effect of boiler oversizing on efficiency: a dynamic simulation study

Gas boilers dominate domestic heating in the UK, and significant efficiency improvements have been associated with condensing boilers. However, the potential remains for further efficiency improvement by refining the control, system specification and installation in real dwellings. Dynamic building simulation modelling, including detailed heating system componentry, enables a deeper analysis of boiler underperformance. This paper explores the link between the space heat oversizing of boilers and on/off cycling using dynamic simulation, and their subsequent effect on boiler efficiency and internal temperatures. At plant size ratio (PSR) 8.5 daily cycles numbered over 50, similar to median levels seen in real homes. Simulations show that typical oversizing (PSR >3) significantly increases cycling behaviour and brings an efficiency penalty of 6–9%. There is a clear link between raising PSR, increased cycling and an associated decreased efficiency; however, in the UK, boilers are regularly oversized with respect to space heating, especially combination boilers to cover peak hot water demand. Current legislation and labelling (ErP and SAP) overlook PSR as a determinant of system efficiency, failing to incentivise appropriate sizing. Reducing boiler oversizing through addressing installation practices and certification has the potential to significantly improve efficiency at low cost, decreasing associated carbon emissions. Practical application: This research provides the basis for a practical and cost effective means of assessing the potential for underperformance of boiler heating systems at the point of installation or refurbishment. By assessing the oversizing of the boiler with respect to space heating, unnecessary cycling and the associated efficiency penalty can be avoided. Plant size ratio, as an indicator of cycling potential, can be implemented in energy performance certificates (EPCs), through the standard assessment procedure (SAP), using existing data. The potential for real carbon savings in the existing boiler stock is considerable, and the findings have wider implications for next generation heating systems

Measure Guideline: Condensing Boilers - Control Strategies for Optimizing Performance and Comfort in Residential Applications

The combination of a gas-fired condensing boiler with baseboard convectors and an indirect water heater has become a common option for high-efficiency residential space heating in cold climates. While there are many condensing boilers available on the market with rated efficiencies in the low to mid 90% efficient range, it is imperative to understand that if the control systems are not properly configured, these heaters will perform no better than their non-condensing counterparts. Based on previous research efforts, it is apparent that these types of systems are typically not designed and installed to achieve maximum efficiency (Arena 2010). It was found that there is a significant lack of information for contractors on how to configure the control systems to optimize overall efficiency. For example, there is little advice on selecting the best settings for the boiler reset curve or how to measure and set flow rates in the system to ensure that the return temperatures are low enough to promote condensing. It has also been observed that recovery from setback can be extremely slow and, at times, not achieved. Recovery can be affected by the outdoor reset control, the differential setting on the boiler and over-sizing of the boiler itself. This guide is intended for designers and installers of hydronic heating systems interested in maximizing the overall system efficiency of condensing boilers when coupled with baseboard convectors. It is applicable to new and retrofit applications

Do domestic heating controls save energy? A review of the evidence

© 2018 The Authors Claims about the benefits of heating controls are often biased, unsubstantiated, misleading, or incorrect. This paper presents a systematic and critical international review of the evidence for the energy saving, cost effectiveness and usability of heating controls. The focus is domestic, low-pressure hot water heating systems in temperate climates. Eleven different types of standard, advanced and smart controls are assessed plus five components and features that add smart functionality. The review retrieved over 2400 documents from on-line databases and other sources. Screening criteria and quality assurance scoring identified just 67 items, mainly from the UK and USA, which appeared to contain relevant evidence. This evidence was derived from computer modelling, field trials and full-scale experiments, and for usability, from expert evaluations and controlled assessments. The evidence was synthesised and its quality classified as very low, low, moderate or high using the GRADE system which is more commonly applied in evidence-based medicine. The energy savings of most heating controls depends strongly on whether the heating system is operated with a continuous or periodic heating pattern, as well as on the energy efficiency of the dwelling and the severity of the climate. For most control types, the quality of the evidence for energy savings was low, very low or non-existent. However, there was moderate quality evidence that, when appropriately commissioned, zonal controllers, which heat individual spaces to different temperatures at different times, could save energy compared to whole-house controllers, and that low-cost systems of this type could be cost-effective. There was moderate quality evidence that smart thermostats do not save energy compared to standard thermostats and programmers and may, in fact, increase energy demand. The usability studies focussed on general heating controls and programmable thermostats and provided high quality evidence that heating controls are difficult to use, especially by older people. However, no studies were uncovered that quantified the consequent energy penalty. There was no high quality evidence about the impact on energy demand of any of the heating controls studied, mainly because there have been no well-founded, large-scale, multi-disciplinary, multi-year field trials