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Environmental Stability and External Environmental Dependency Analysis of Vertical Farm Remodeled from Agricultural Shelter House

농막하우스 리모델링 수직농장의 환경 안정성 및 외부환경 의존성 분석

Jong-Hee Lee1
,
Sunwoo Park2*
이 종희1
,
박 선우2*
1Department of Digital Agricultural Promotion, Agricultural Cooperative University, Goyang 10292, Korea
2Department of Cooperative Digital Management, Agricultural Cooperative University, Goyang 10292, Korea
1농협대학교 디지털농업추진단
2농협대학교 협동조합경영과
*Corresponding Author
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Abstract

This study proposes a model for constructing an energy-efficient vertical farm by retrofitting an existing agricultural facility, specifically an Agricultural Shelter House (“Nongmak house”), and evaluates its performance. An eight-layer composite thermal insulation covering system was applied to a 231 m2 (70 pyeong) agricultural shelter house, which was converted into a closed-type vertical farm. To quantitatively assess the thermal insulation performance and environmental stability of the retrofitted system, the U-value was measured, and the internal and external environmental data were analyzed. Environmental stability was defined as the degree to which optimal internal environments (temperature, humidity, etc.) for crop growth can be maintained within a certain range regardless of external environmental changes, which is essential for minimizing crop stress and creating efficient cultivation environments. The calculated U-value of the composite insulation system was 1.939 W/m2·K. Although this value does not reach the level of conventional container-type vertical farms (0.193–0.225 W/m2·K), it exhibits superior performance compared to single-layer PE film greenhouses (6.476 W/m2·K) and high-performance triple-layer thermal curtain systems (2.73 W/m2·K). Furthermore, the analysis of external climate, conventional greenhouse, and vertical farm internal environments demonstrated that the retrofitted vertical farm maintained highly stable conditions, with a temperature coefficient of variation (CV) of 5.85% and a relative humidity CV of 11.58%. Compared to external and conventional greenhouse environments, this structure provided significantly enhanced environmental stability. Statistical analysis using independent t-tests confirmed that the vertical farm showed significantly more stable temperature (t = -17.370, p < 0.001) and humidity (t = 40.163, p < 0.001) compared to conventional greenhouse systems. Time-series analysis further revealed that the internal environment of the vertical farm remained consistent throughout seasonal changes (temperature CV: 1.16–1.38%). Correlation analysis with expanded external environmental variables showed minimal dependency on solar radiation (γ = 0.372), wind speed (γ = 0.196), and external temperature (γ = 0.315), confirming the independence from external conditions. Additionally, the total heat load generated in the vertical farm was calculated as approximately 22.17 kW, consisting of sensible heat load (12.34 kW) from LED growth lights and latent heat load (9.83 kW) from crop transpiration. This represents sufficient margin compared to the total rated cooling capacity (155 kW) of the temperature and humidity control units, confirming adequate cooling performance. Although the thermal insulation performance of the retrofitted system does not fully match that of commercial container-type vertical farms, it is sufficient to maintain a controlled environment year-round. These results suggest that the proposed system can provide both cost-effective initial investment and improved energy efficiency while ensuring stable environmental control. These findings indicate that this retrofitting approach offers a practical and economical alternative for advancing the viability of vertical farms and can promote the adoption of such technologies among small- and medium-scale farmers.

Keywords
coefficient of variation
energy efficiency
retrofitting
small-scale farming
thermal insulation
u-value

본 연구에서는 기존 농업시설인 농막하우스를 리모델링하여 에너지 효율적인 수직농장을 구축하는 모델을 제시하고 그 성능을 평가하였다. 70평 규모(약 231m2)의 농막하우스에 8겹의 복합 단열 피복 시스템을 적용하여 밀폐형 수직농장으로 전환하였으며, 현재 운영중인 시스템의 단열 성능과 환경안정성을 정량적으로 평가하기 위해 열관류율(U-value)을 산출하고, 내･외부 환경데이터를 분석하였다. 복합 단열 피복 시스템의 열관류율은 1.939W/m2·K로 산출되었다. 이는 일반 컨테이너형 수직농장(0.193–0.225W/m2·K)의 수준에는 미치지 못하지만 일반 단층 PE필름 온실(6.476W/m2·K), 고성능 3중 보온커튼 시스템(2.73W/m2·K)보다 높은 성능으로 나타냈다. 또한 외기환경, 기존 온실 내부 환경, 수직농장의 내부환경 데이터를 분석한 결과, 농막하우스형 수직농장은 온도 변동계수(CV) 5.85%, 습도 변동계수 11.58%로 매우 안정적인 환경을 유지하였다. 이는 외부환경 및 연동형 온실과 비교하여 현저히 우수한 환경 안정성을 나타내었으며, 독립표본 t-검정 결과 통계적으로 유의한 차이를 확인하였다(온도: t = –17.370, p < 0.001; 습도: t = 40.163, p < 0.001). 시계열 분석에서도 수직농장은 계절 변화에 관계없이 일정한 환경을 유지(온도 CV: 1.16–1.38%)하였다. 확대된 외부환경 변수와의 상관관계 분석 결과, 일사량(γ = 0.372), 풍속(γ = 0.196), 외부온도(γ = 0.315)에 대해 낮은 상관관계를 보여 외부환경으로부터의 독립성을 확인하였다. 또한, 수직농장에서 발생하는 총 열부하(LED 생육등에 의한 현열부하(12.34kW)와 작물 증산에 의한 잠열부하(9.83kW)) 약 22.17kW로 산출되었는데, 이는 항온항습장치의 총 정격냉방능력(155kW)에 대해 충분한 여유가 있어 냉방성능은 충분한 것으로 확인되었다. 농막하우스형 수직농장은 비록 절대적인 단열성능은 기존 컨테이너형 수직농장에 미치지 못하지만, 연중 환경제어가 가능할 정도로 충분한 단열성능을 확보하여 초기 투자비용 절감과 동시에 안정적인 환경제어와 에너지 효율성을 달성할 수 있음을 시사한다. 이러한 결과는 수직농장형 스마트팜의 경제성을 확보하고 중소 농업인들에게 기술 도입을 촉진할 수 있는 실용적 대안이 될 것으로 사료된다.

키워드
변동계수
에너지 효율성
리모델링
소규모 농업
열절연
열관류율
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Information
  • Publisher :KOREAN SOCIETY FOR HORTICULTURAL SCIENCE
  • Publisher(Ko) :한국원예학회
  • Journal Title :Horticultural Science and Technology
  • Journal Title(Ko) :원예과학기술지
  • Received Date : 2025-07-14
  • Revised Date : 2025-11-26
  • Accepted Date : 2025-12-05
  • DOI :https://doi.org/10.7235/HORT.20250080
Journal Informaiton Horticultural Science and Technology Horticultural Science and Technology
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